krb5: fix for CVE-2024-3596

Upstream-Status: Backport from https://github.com/krb5/krb5/commit/871125fea8ce0370a972bf65f7d1de63f619b06c

Signed-off-by: Hitendra Prajapati <hprajapati@mvista.com>
Signed-off-by: Gyorgy Sarvari <skandigraun@gmail.com>

2 files changed, 629 insertions, 0 deletions

diff --git a/meta-oe/recipes-connectivity/krb5/krb5/CVE-2024-3596.patch b/meta-oe/recipes-connectivity/krb5/krb5/CVE-2024-3596.patch
new file mode 100644
index 0000000000..8e74b07aef
--- /dev/null
+++ b/meta-oe/recipes-connectivity/krb5/krb5/CVE-2024-3596.patch
@@ -0,0 +1,628 @@
+From 871125fea8ce0370a972bf65f7d1de63f619b06c Mon Sep 17 00:00:00 2001
+From: Julien Rische <jrische@redhat.com>
+Date: Thu, 22 Aug 2024 17:15:50 +0200
+Subject: [PATCH] Generate and verify message MACs in libkrad
+
+Implement some of the measures specified in
+draft-ietf-radext-deprecating-radius-03 for mitigating the BlastRADIUS
+attack (CVE-2024-3596):
+
+* Include a Message-Authenticator MAC as the first attribute when
+  generating a packet of type Access-Request, Access-Reject,
+  Access-Accept, or Access-Challenge (sections 5.2.1 and 5.2.4), if
+  the secret is non-empty.  (An empty secret indicates the use of Unix
+  domain socket transport.)
+
+* Validate the Message-Authenticator MAC in received packets, if
+  present.
+
+FreeRADIUS enforces Message-Authenticator as of versions 3.2.5 and
+3.0.27.  libkrad must generate Message-Authenticator attributes in
+order to remain compatible with these implementations.
+
+[ghudson@mit.edu: adjusted style and naming; simplified some
+functions; edited commit message]
+
+ticket: 9142 (new)
+tags: pullup
+target_version: 1.21-next
+
+CVE: CVE-2024-3596
+Upstream-Status: Backport [https://github.com/krb5/krb5/commit/871125fea8ce0370a972bf65f7d1de63f619b06c]
+Signed-off-by: Hitendra Prajapati <hprajapati@mvista.com>
+---
+ src/include/k5-int.h                   |   5 +
+ src/lib/crypto/krb/checksum_hmac_md5.c |  28 ++++
+ src/lib/crypto/libk5crypto.exports     |   1 +
+ src/lib/krad/attr.c                    |  17 ++
+ src/lib/krad/attrset.c                 |  58 +++++--
+ src/lib/krad/internal.h                |   7 +-
+ src/lib/krad/packet.c                  | 205 +++++++++++++++++++++++--
+ src/lib/krad/t_attrset.c               |   2 +-
+ src/lib/krad/t_daemon.py               |   3 +-
+ src/lib/krad/t_packet.c                |  11 ++
+ src/tests/t_otp.py                     |   3 +
+ 11 files changed, 309 insertions(+), 31 deletions(-)
+
+diff --git a/src/include/k5-int.h b/src/include/k5-int.h
+index 5928c82..9b3aa13 100644
+--- a/src/include/k5-int.h
++++ b/src/include/k5-int.h
+@@ -2394,4 +2394,9 @@ void k5_change_error_message_code(krb5_context ctx, krb5_error_code oldcode,
+ #define k5_prependmsg krb5_prepend_error_message
+ #define k5_wrapmsg krb5_wrap_error_message
+ 
++/* Generate an HMAC-MD5 keyed checksum as specified by RFC 2104. */
++krb5_error_code
++k5_hmac_md5(const krb5_data *key, const krb5_crypto_iov *data, size_t num_data,
++            krb5_data *output);
++
+ #endif /* _KRB5_INT_H */
+diff --git a/src/lib/crypto/krb/checksum_hmac_md5.c b/src/lib/crypto/krb/checksum_hmac_md5.c
+index ec024f3..a809388 100644
+--- a/src/lib/crypto/krb/checksum_hmac_md5.c
++++ b/src/lib/crypto/krb/checksum_hmac_md5.c
+@@ -92,3 +92,31 @@ cleanup:
+     free(hash_iov);
+     return ret;
+ }
++
++krb5_error_code
++k5_hmac_md5(const krb5_data *key, const krb5_crypto_iov *data, size_t num_data,
++            krb5_data *output)
++{
++    krb5_error_code ret;
++    const struct krb5_hash_provider *hash = &krb5int_hash_md5;
++    krb5_keyblock keyblock = { 0 };
++    krb5_data hashed_key;
++    uint8_t hkeybuf[16];
++    krb5_crypto_iov iov;
++
++    /* Hash the key if it is longer than the block size. */
++    if (key->length > hash->blocksize) {
++        hashed_key = make_data(hkeybuf, sizeof(hkeybuf));
++        iov.flags = KRB5_CRYPTO_TYPE_DATA;
++        iov.data = *key;
++        ret = hash->hash(&iov, 1, &hashed_key);
++        if (ret)
++            return ret;
++        key = &hashed_key;
++    }
++
++    keyblock.magic = KV5M_KEYBLOCK;
++    keyblock.length = key->length;
++    keyblock.contents = (uint8_t *)key->data;
++    return krb5int_hmac_keyblock(hash, &keyblock, data, num_data, output);
++}
+diff --git a/src/lib/crypto/libk5crypto.exports b/src/lib/crypto/libk5crypto.exports
+index 90afdf5..02efa3b 100644
+--- a/src/lib/crypto/libk5crypto.exports
++++ b/src/lib/crypto/libk5crypto.exports
+@@ -110,3 +110,4 @@ krb5_c_prfplus
+ krb5_c_derive_prfplus
+ k5_enctype_to_ssf
+ krb5int_c_deprecated_enctype
++k5_hmac_md5
+diff --git a/src/lib/krad/attr.c b/src/lib/krad/attr.c
+index 9c13d9d..4ad3212 100644
+--- a/src/lib/krad/attr.c
++++ b/src/lib/krad/attr.c
+@@ -122,6 +122,23 @@ static const attribute_record attributes[UCHAR_MAX] = {
+     {"NAS-Port-Type", 4, 4, NULL, NULL},
+     {"Port-Limit", 4, 4, NULL, NULL},
+     {"Login-LAT-Port", 1, MAX_ATTRSIZE, NULL, NULL},
++    {NULL, 0, 0, NULL, NULL}, /* Reserved for tunnelling */
++    {NULL, 0, 0, NULL, NULL}, /* Reserved for tunnelling */
++    {NULL, 0, 0, NULL, NULL}, /* Reserved for tunnelling */
++    {NULL, 0, 0, NULL, NULL}, /* Reserved for tunnelling */
++    {NULL, 0, 0, NULL, NULL}, /* Reserved for tunnelling */
++    {NULL, 0, 0, NULL, NULL}, /* Reserved for tunnelling */
++    {NULL, 0, 0, NULL, NULL}, /* Reserved for Apple Remote Access Protocol */
++    {NULL, 0, 0, NULL, NULL}, /* Reserved for Apple Remote Access Protocol */
++    {NULL, 0, 0, NULL, NULL}, /* Reserved for Apple Remote Access Protocol */
++    {NULL, 0, 0, NULL, NULL}, /* Reserved for Apple Remote Access Protocol */
++    {NULL, 0, 0, NULL, NULL}, /* Reserved for Apple Remote Access Protocol */
++    {NULL, 0, 0, NULL, NULL}, /* Password-Retry */
++    {NULL, 0, 0, NULL, NULL}, /* Prompt */
++    {NULL, 0, 0, NULL, NULL}, /* Connect-Info */
++    {NULL, 0, 0, NULL, NULL}, /* Configuration-Token */
++    {NULL, 0, 0, NULL, NULL}, /* EAP-Message */
++    {"Message-Authenticator", MD5_DIGEST_SIZE, MD5_DIGEST_SIZE, NULL, NULL},
+ };
+ 
+ /* Encode User-Password attribute. */
+diff --git a/src/lib/krad/attrset.c b/src/lib/krad/attrset.c
+index 03c6137..f279949 100644
+--- a/src/lib/krad/attrset.c
++++ b/src/lib/krad/attrset.c
+@@ -164,14 +164,42 @@ krad_attrset_copy(const krad_attrset *set, krad_attrset **copy)
+     return 0;
+ }
+ 
++/* Place an encoded attributes into outbuf at position *i.  Increment *i by the
++ * length of the encoding. */
++static krb5_error_code
++append_attr(krb5_context ctx, const char *secret,
++            const uint8_t *auth, krad_attr type, const krb5_data *data,
++            uint8_t outbuf[MAX_ATTRSETSIZE], size_t *i)
++{
++    uint8_t buffer[MAX_ATTRSIZE];
++    size_t attrlen;
++    krb5_error_code retval;
++
++    retval = kr_attr_encode(ctx, secret, auth, type, data, buffer, &attrlen);
++    if (retval)
++        return retval;
++
++    if (attrlen > MAX_ATTRSETSIZE - *i - 2)
++        return EMSGSIZE;
++
++    outbuf[(*i)++] = type;
++    outbuf[(*i)++] = attrlen + 2;
++    memcpy(outbuf + *i, buffer, attrlen);
++    *i += attrlen;
++
++    return 0;
++}
++
+ krb5_error_code
+ kr_attrset_encode(const krad_attrset *set, const char *secret,
+-                  const unsigned char *auth,
++                  const uint8_t *auth, krb5_boolean add_msgauth,
+                   unsigned char outbuf[MAX_ATTRSETSIZE], size_t *outlen)
+ {
+-    unsigned char buffer[MAX_ATTRSIZE];
+     krb5_error_code retval;
+-    size_t i = 0, attrlen;
++    krad_attr msgauth_type = krad_attr_name2num("Message-Authenticator");
++    const uint8_t zeroes[MD5_DIGEST_SIZE] = { 0 };
++    krb5_data zerodata;
++    size_t i = 0;
+     attr *a;
+ 
+     if (set == NULL) {
+@@ -179,19 +207,21 @@ kr_attrset_encode(const krad_attrset *set, const char *secret,
+         return 0;
+     }
+ 
+-    K5_TAILQ_FOREACH(a, &set->list, list) {
+-        retval = kr_attr_encode(set->ctx, secret, auth, a->type, &a->attr,
+-                                buffer, &attrlen);
+-        if (retval != 0)
++    if (add_msgauth) {
++        /* Encode Message-Authenticator as the first attribute, per
++         * draft-ietf-radext-deprecating-radius-03 section 5.2. */
++        zerodata = make_data((uint8_t *)zeroes, MD5_DIGEST_SIZE);
++        retval = append_attr(set->ctx, secret, auth, msgauth_type, &zerodata,
++                             outbuf, &i);
++        if (retval)
+             return retval;
++    }
+ 
+-        if (i + attrlen + 2 > MAX_ATTRSETSIZE)
+-            return EMSGSIZE;
+-
+-        outbuf[i++] = a->type;
+-        outbuf[i++] = attrlen + 2;
+-        memcpy(&outbuf[i], buffer, attrlen);
+-        i += attrlen;
++    K5_TAILQ_FOREACH(a, &set->list, list) {
++        retval = append_attr(set->ctx, secret, auth, a->type, &a->attr,
++                             outbuf, &i);
++        if (retval)
++            return retval;
+     }
+ 
+     *outlen = i;
+diff --git a/src/lib/krad/internal.h b/src/lib/krad/internal.h
+index 996a893..8194b00 100644
+--- a/src/lib/krad/internal.h
++++ b/src/lib/krad/internal.h
+@@ -43,6 +43,8 @@
+ #define UCHAR_MAX 255
+ #endif
+ 
++#define MD5_DIGEST_SIZE 16
++
+ /* RFC 2865 */
+ #define MAX_ATTRSIZE (UCHAR_MAX - 2)
+ #define MAX_ATTRSETSIZE (KRAD_PACKET_SIZE_MAX - 20)
+@@ -65,10 +67,11 @@ kr_attr_decode(krb5_context ctx, const char *secret, const unsigned char *auth,
+                krad_attr type, const krb5_data *in,
+                unsigned char outbuf[MAX_ATTRSIZE], size_t *outlen);
+ 
+-/* Encode the attributes into the buffer. */
++/* Encode set into outbuf.  If add_msgauth is true, include a zeroed
++ * Message-Authenticator as the first attribute. */
+ krb5_error_code
+ kr_attrset_encode(const krad_attrset *set, const char *secret,
+-                  const unsigned char *auth,
++                  const uint8_t *auth, krb5_boolean add_msgauth,
+                   unsigned char outbuf[MAX_ATTRSETSIZE], size_t *outlen);
+ 
+ /* Decode attributes from a buffer. */
+diff --git a/src/lib/krad/packet.c b/src/lib/krad/packet.c
+index c597174..539af5a 100644
+--- a/src/lib/krad/packet.c
++++ b/src/lib/krad/packet.c
+@@ -36,6 +36,7 @@
+ typedef unsigned char uchar;
+ 
+ /* RFC 2865 */
++#define MSGAUTH_SIZE (2 + MD5_DIGEST_SIZE)
+ #define OFFSET_CODE 0
+ #define OFFSET_ID 1
+ #define OFFSET_LENGTH 2
+@@ -222,6 +223,106 @@ packet_set_attrset(krb5_context ctx, const char *secret, krad_packet *pkt)
+     return kr_attrset_decode(ctx, &tmp, secret, pkt_auth(pkt), &pkt->attrset);
+ }
+ 
++/* Determine if a packet requires a Message-Authenticator attribute. */
++static inline krb5_boolean
++requires_msgauth(const char *secret, krad_code code)
++{
++    /* If no secret is provided, assume that the transport is a UNIX socket.
++     * Message-Authenticator is required only on UDP and TCP connections. */
++    if (*secret == '\0')
++        return FALSE;
++
++    /*
++     * Per draft-ietf-radext-deprecating-radius-03 sections 5.2.1 and 5.2.4,
++     * Message-Authenticator is required in Access-Request packets and all
++     * potential responses when UDP or TCP transport is used.
++     */
++    return code == krad_code_name2num("Access-Request") ||
++        code == krad_code_name2num("Access-Reject") ||
++        code == krad_code_name2num("Access-Accept") ||
++        code == krad_code_name2num("Access-Challenge");
++}
++
++/* Check if the packet has a Message-Authenticator attribute. */
++static inline krb5_boolean
++has_pkt_msgauth(const krad_packet *pkt)
++{
++    krad_attr msgauth_type = krad_attr_name2num("Message-Authenticator");
++
++    return krad_attrset_get(pkt->attrset, msgauth_type, 0) != NULL;
++}
++
++/* Return the beginning of the Message-Authenticator attribute in pkt, or NULL
++ * if no such attribute is present. */
++static const uint8_t *
++lookup_msgauth_addr(const krad_packet *pkt)
++{
++    krad_attr msgauth_type = krad_attr_name2num("Message-Authenticator");
++    size_t i;
++    uint8_t *p;
++
++    i = OFFSET_ATTR;
++    while (i + 2 < pkt->pkt.length) {
++        p = (uint8_t *)offset(&pkt->pkt, i);
++        if (msgauth_type == *p)
++            return p;
++        i += p[1];
++    }
++
++    return NULL;
++}
++
++/*
++ * Calculate the message authenticator MAC for pkt as specified in RFC 2869
++ * section 5.14, placing the result in mac_out.  Use the provided authenticator
++ * auth, which may be from pkt or from a corresponding request.
++ */
++static krb5_error_code
++calculate_mac(const char *secret, const krad_packet *pkt,
++              const uint8_t auth[AUTH_FIELD_SIZE],
++              uint8_t mac_out[MD5_DIGEST_SIZE])
++{
++    uint8_t zeroed_msgauth[MSGAUTH_SIZE];
++    krad_attr msgauth_type = krad_attr_name2num("Message-Authenticator");
++    const uint8_t *msgauth_attr, *msgauth_end, *pkt_end;
++    krb5_crypto_iov input[5];
++    krb5_data ksecr, mac;
++
++    msgauth_attr = lookup_msgauth_addr(pkt);
++    if (msgauth_attr == NULL)
++        return EINVAL;
++    msgauth_end = msgauth_attr + MSGAUTH_SIZE;
++    pkt_end = (const uint8_t *)pkt->pkt.data + pkt->pkt.length;
++
++    /* Read code, id, and length from the packet. */
++    input[0].flags = KRB5_CRYPTO_TYPE_DATA;
++    input[0].data = make_data(pkt->pkt.data, OFFSET_AUTH);
++
++    /* Read the provided authenticator. */
++    input[1].flags = KRB5_CRYPTO_TYPE_DATA;
++    input[1].data = make_data((uint8_t *)auth, AUTH_FIELD_SIZE);
++
++    /* Read any attributes before Message-Authenticator. */
++    input[2].flags = KRB5_CRYPTO_TYPE_DATA;
++    input[2].data = make_data(pkt_attr(pkt), msgauth_attr - pkt_attr(pkt));
++
++    /* Read Message-Authenticator with the data bytes all set to zero, per RFC
++     * 2869 section 5.14. */
++    zeroed_msgauth[0] = msgauth_type;
++    zeroed_msgauth[1] = MSGAUTH_SIZE;
++    memset(zeroed_msgauth + 2, 0, MD5_DIGEST_SIZE);
++    input[3].flags = KRB5_CRYPTO_TYPE_DATA;
++    input[3].data = make_data(zeroed_msgauth, MSGAUTH_SIZE);
++
++    /* Read any attributes after Message-Authenticator. */
++    input[4].flags = KRB5_CRYPTO_TYPE_DATA;
++    input[4].data = make_data((uint8_t *)msgauth_end, pkt_end - msgauth_end);
++
++    mac = make_data(mac_out, MD5_DIGEST_SIZE);
++    ksecr = string2data((char *)secret);
++    return k5_hmac_md5(&ksecr, input, 5, &mac);
++}
++
+ ssize_t
+ krad_packet_bytes_needed(const krb5_data *buffer)
+ {
+@@ -255,6 +356,7 @@ krad_packet_new_request(krb5_context ctx, const char *secret, krad_code code,
+     krad_packet *pkt;
+     uchar id;
+     size_t attrset_len;
++    krb5_boolean msgauth_required;
+ 
+     pkt = packet_new();
+     if (pkt == NULL) {
+@@ -274,9 +376,13 @@ krad_packet_new_request(krb5_context ctx, const char *secret, krad_code code,
+     if (retval != 0)
+         goto error;
+ 
++    /* Determine if Message-Authenticator is required. */
++    msgauth_required = (*secret != '\0' &&
++                        code == krad_code_name2num("Access-Request"));
++
+     /* Encode the attributes. */
+-    retval = kr_attrset_encode(set, secret, pkt_auth(pkt), pkt_attr(pkt),
+-                               &attrset_len);
++    retval = kr_attrset_encode(set, secret, pkt_auth(pkt), msgauth_required,
++                               pkt_attr(pkt), &attrset_len);
+     if (retval != 0)
+         goto error;
+ 
+@@ -285,6 +391,13 @@ krad_packet_new_request(krb5_context ctx, const char *secret, krad_code code,
+     pkt_code_set(pkt, code);
+     pkt_len_set(pkt, pkt->pkt.length);
+ 
++    if (msgauth_required) {
++        /* Calculate and set the Message-Authenticator MAC. */
++        retval = calculate_mac(secret, pkt, pkt_auth(pkt), pkt_attr(pkt) + 2);
++        if (retval != 0)
++            goto error;
++    }
++
+     /* Copy the attrset for future use. */
+     retval = packet_set_attrset(ctx, secret, pkt);
+     if (retval != 0)
+@@ -307,14 +420,18 @@ krad_packet_new_response(krb5_context ctx, const char *secret, krad_code code,
+     krb5_error_code retval;
+     krad_packet *pkt;
+     size_t attrset_len;
++    krb5_boolean msgauth_required;
+ 
+     pkt = packet_new();
+     if (pkt == NULL)
+         return ENOMEM;
+ 
++    /* Determine if Message-Authenticator is required. */
++    msgauth_required = requires_msgauth(secret, code);
++
+     /* Encode the attributes. */
+-    retval = kr_attrset_encode(set, secret, pkt_auth(request), pkt_attr(pkt),
+-                               &attrset_len);
++    retval = kr_attrset_encode(set, secret, pkt_auth(request),
++                               msgauth_required, pkt_attr(pkt), &attrset_len);
+     if (retval != 0)
+         goto error;
+ 
+@@ -330,6 +447,18 @@ krad_packet_new_response(krb5_context ctx, const char *secret, krad_code code,
+     if (retval != 0)
+         goto error;
+ 
++    if (msgauth_required) {
++        /*
++         * Calculate and replace the Message-Authenticator MAC.  Per RFC 2869
++         * section 5.14, use the authenticator from the request, not from the
++         * response.
++         */
++        retval = calculate_mac(secret, pkt, pkt_auth(request),
++                               pkt_attr(pkt) + 2);
++        if (retval != 0)
++            goto error;
++    }
++
+     /* Copy the attrset for future use. */
+     retval = packet_set_attrset(ctx, secret, pkt);
+     if (retval != 0)
+@@ -343,6 +472,34 @@ error:
+     return retval;
+ }
+ 
++/* Verify the Message-Authenticator value in pkt, using the provided
++ * authenticator (which may be from pkt or from a corresponding request). */
++static krb5_error_code
++verify_msgauth(const char *secret, const krad_packet *pkt,
++               const uint8_t auth[AUTH_FIELD_SIZE])
++{
++    uint8_t mac[MD5_DIGEST_SIZE];
++    krad_attr msgauth_type = krad_attr_name2num("Message-Authenticator");
++    const krb5_data *msgauth;
++    krb5_error_code retval;
++
++    msgauth = krad_packet_get_attr(pkt, msgauth_type, 0);
++    if (msgauth == NULL)
++        return ENODATA;
++
++    retval = calculate_mac(secret, pkt, auth, mac);
++    if (retval)
++        return retval;
++
++    if (msgauth->length != MD5_DIGEST_SIZE)
++        return EMSGSIZE;
++
++    if (k5_bcmp(mac, msgauth->data, MD5_DIGEST_SIZE) != 0)
++        return EBADMSG;
++
++    return 0;
++}
++
+ /* Decode a packet. */
+ static krb5_error_code
+ decode_packet(krb5_context ctx, const char *secret, const krb5_data *buffer,
+@@ -394,21 +551,35 @@ krad_packet_decode_request(krb5_context ctx, const char *secret,
+                            krad_packet **reqpkt)
+ {
+     const krad_packet *tmp = NULL;
++    krad_packet *req;
+     krb5_error_code retval;
+ 
+-    retval = decode_packet(ctx, secret, buffer, reqpkt);
+-    if (cb != NULL && retval == 0) {
++    retval = decode_packet(ctx, secret, buffer, &req);
++    if (retval)
++        return retval;
++
++    /* Verify Message-Authenticator if present. */
++    if (has_pkt_msgauth(req)) {
++        retval = verify_msgauth(secret, req, pkt_auth(req));
++        if (retval) {
++            krad_packet_free(req);
++            return retval;
++        }
++    }
++
++    if (cb != NULL) {
+         for (tmp = (*cb)(data, FALSE); tmp != NULL; tmp = (*cb)(data, FALSE)) {
+             if (pkt_id_get(*reqpkt) == pkt_id_get(tmp))
+                 break;
+         }
+-    }
+ 
+-    if (cb != NULL && (retval != 0 || tmp != NULL))
+-        (*cb)(data, TRUE);
++        if (tmp != NULL)
++            (*cb)(data, TRUE);
++    }
+ 
++    *reqpkt = req;
+     *duppkt = tmp;
+-    return retval;
++    return 0;
+ }
+ 
+ krb5_error_code
+@@ -435,9 +606,17 @@ krad_packet_decode_response(krb5_context ctx, const char *secret,
+                 break;
+             }
+ 
+-            /* If the authenticator matches, then the response is valid. */
+-            if (memcmp(pkt_auth(*rsppkt), auth, sizeof(auth)) == 0)
+-                break;
++            /* Verify the response authenticator. */
++            if (k5_bcmp(pkt_auth(*rsppkt), auth, sizeof(auth)) != 0)
++                continue;
++
++            /* Verify Message-Authenticator if present. */
++            if (has_pkt_msgauth(*rsppkt)) {
++                if (verify_msgauth(secret, *rsppkt, pkt_auth(tmp)) != 0)
++                    continue;
++            }
++
++            break;
+         }
+     }
+ 
+diff --git a/src/lib/krad/t_attrset.c b/src/lib/krad/t_attrset.c
+index 7928335..fd11ee5 100644
+--- a/src/lib/krad/t_attrset.c
++++ b/src/lib/krad/t_attrset.c
+@@ -62,7 +62,7 @@ main()
+     noerror(krad_attrset_add(set, krad_attr_name2num("User-Password"), &tmp));
+ 
+     /* Encode attrset. */
+-    noerror(kr_attrset_encode(set, "foo", auth, buffer, &encode_len));
++    noerror(kr_attrset_encode(set, "foo", auth, FALSE, buffer, &encode_len));
+     krad_attrset_free(set);
+ 
+     /* Manually encode User-Name. */
+diff --git a/src/lib/krad/t_daemon.py b/src/lib/krad/t_daemon.py
+index 7668cd7..7fa0449 100755
+--- a/src/lib/krad/t_daemon.py
++++ b/src/lib/krad/t_daemon.py
+@@ -40,6 +40,7 @@ DICTIONARY = """
+ ATTRIBUTE\tUser-Name\t1\tstring
+ ATTRIBUTE\tUser-Password\t2\toctets
+ ATTRIBUTE\tNAS-Identifier\t32\tstring
++ATTRIBUTE\tMessage-Authenticator\t80\toctets
+ """
+ 
+ class TestServer(server.Server):
+@@ -52,7 +53,7 @@ class TestServer(server.Server):
+             if key == "User-Password":
+                 passwd = map(pkt.PwDecrypt, pkt[key])
+ 
+-        reply = self.CreateReplyPacket(pkt)
++        reply = self.CreateReplyPacket(pkt, message_authenticator=True)
+         if passwd == ['accept']:
+             reply.code = packet.AccessAccept
+         else:
+diff --git a/src/lib/krad/t_packet.c b/src/lib/krad/t_packet.c
+index 0a92e9c..745fb21 100644
+--- a/src/lib/krad/t_packet.c
++++ b/src/lib/krad/t_packet.c
+@@ -159,6 +159,9 @@ main(int argc, const char **argv)
+     krb5_data username, password;
+     krb5_boolean auth = FALSE;
+     krb5_context ctx;
++    const krad_packet *dupreq;
++    const krb5_data *encpkt;
++    krad_packet *decreq;
+ 
+     username = string2data("testUser");
+ 
+@@ -171,9 +174,17 @@ main(int argc, const char **argv)
+ 
+     password = string2data("accept");
+     noerror(make_packet(ctx, &username, &password, &packets[ACCEPT_PACKET]));
++    encpkt = krad_packet_encode(packets[ACCEPT_PACKET]);
++    noerror(krad_packet_decode_request(ctx, "foo", encpkt, NULL, NULL,
++                                       &dupreq, &decreq));
++    krad_packet_free(decreq);
+ 
+     password = string2data("reject");
+     noerror(make_packet(ctx, &username, &password, &packets[REJECT_PACKET]));
++    encpkt = krad_packet_encode(packets[REJECT_PACKET]);
++    noerror(krad_packet_decode_request(ctx, "foo", encpkt, NULL, NULL,
++                                       &dupreq, &decreq));
++    krad_packet_free(decreq);
+ 
+     memset(&hints, 0, sizeof(hints));
+     hints.ai_family = AF_INET;
+diff --git a/src/tests/t_otp.py b/src/tests/t_otp.py
+index cba871a..1ec9165 100755
+--- a/src/tests/t_otp.py
++++ b/src/tests/t_otp.py
+@@ -49,6 +49,7 @@ ATTRIBUTE    User-Name    1    string
+ ATTRIBUTE    User-Password   2    octets
+ ATTRIBUTE    Service-Type    6    integer
+ ATTRIBUTE    NAS-Identifier  32    string
++ATTRIBUTE    Message-Authenticator 80 octets
+ '''
+ 
+ class RadiusDaemon(Process):
+@@ -97,6 +98,8 @@ class RadiusDaemon(Process):
+             reply.code = packet.AccessReject
+             replyq['reply'] = False
+ 
++        reply.add_message_authenticator()
++
+         outq.put(replyq)
+         if addr is None:
+             sock.send(reply.ReplyPacket())
+-- 
+2.50.1
+
diff --git a/meta-oe/recipes-connectivity/krb5/krb5_1.17.2.bb b/meta-oe/recipes-connectivity/krb5/krb5_1.17.2.bb
index d889855649..ed17b57b19 100644
--- a/meta-oe/recipes-connectivity/krb5/krb5_1.17.2.bb
+++ b/meta-oe/recipes-connectivity/krb5/krb5_1.17.2.bb
@@ -41,6 +41,7 @@ SRC_URI = "http://web.mit.edu/kerberos/dist/${BPN}/${SHRT_VER}/${BP}.tar.gz \
            file://CVE-2025-3576-01.patch;striplevel=2 \
            file://CVE-2025-3576-02.patch;striplevel=2 \
            file://CVE-2025-24528.patch;striplevel=2 \
+           file://CVE-2024-3596.patch;striplevel=2 \
 "
 SRC_URI[md5sum] = "aa4337fffa3b61f22dbd0167f708818f"
 SRC_URI[sha256sum] = "1a4bba94df92f6d39a197a10687653e8bfbc9a2076e129f6eb92766974f86134"