From 39daba5e247ea495f88b0be82f0b7ebbdbf50fba Mon Sep 17 00:00:00 2001 From: John Thacker Date: Sat, 26 Jul 2025 07:10:28 -0400 Subject: [PATCH] ssh: Add a null check Fix #20642 Upstream-Status: Backport [https://gitlab.com/wireshark/wireshark/-/commit/39daba5e247ea495f88b0be82f0b7ebbdbf50fba] CVE: CVE-2025-9817 Signed-off-by: Vijay Anusuri --- epan/dissectors/packet-ssh.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/epan/dissectors/packet-ssh.c b/epan/dissectors/packet-ssh.c index 4f2b0ff..9b3b904 100644 --- a/epan/dissectors/packet-ssh.c +++ b/epan/dissectors/packet-ssh.c @@ -2359,6 +2359,10 @@ ssh_kex_shared_secret(gint kex_type, ssh_bignum *pub, ssh_bignum *priv, ssh_bign } if(kex_type==SSH_KEX_DH_GEX){ + if (modulo == NULL) { + ws_debug("Missing group modulo"); + return NULL; + } gcry_mpi_t b = NULL; gcry_mpi_scan(&b, GCRYMPI_FMT_USG, pub->data, pub->length, NULL); gcry_mpi_t d = NULL, e = NULL, m = NULL; -- 2.43.0