python3-dotenv: Fix CVE-2026-28684

Backported from [1], verified with the test script from [2].

[1] https://github.com/theskumar/python-dotenv/commit/790c5c02991100aa1bf41ee5330aca75edc51311
[2] https://github.com/theskumar/python-dotenv/security/advisories/GHSA-mf9w-mj56-hr94
[3] https://nvd.nist.gov/vuln/detail/CVE-2026-28684

Signed-off-by: Bin Cao <bin.cao.cn@windriver.com>
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>

2 files changed, 364 insertions, 0 deletions

diff --git a/recipes-devtools/python/python3-dotenv/CVE-2026-28684.patch b/recipes-devtools/python/python3-dotenv/CVE-2026-28684.patch
new file mode 100644
index 00000000..3302c32e
--- /dev/null
+++ b/recipes-devtools/python/python3-dotenv/CVE-2026-28684.patch
@@ -0,0 +1,363 @@
+From 3fbba98d80cb3c6bfacf708923c79b9ee8a1489c Mon Sep 17 00:00:00 2001
+From: Bin Cao <bin.cao.cn@windriver.com>
+Date: Wed, 29 Apr 2026 11:13:56 +0800
+Subject: [PATCH] Fix symlink following in set_key/unset_key
+
+python-dotenv reads key-value pairs from a .env file and can set them as
+environment variables. set_key() and unset_key() follow symbolic links
+when rewriting .env files via shutil.move(), allowing a local attacker
+to overwrite arbitrary files via a crafted symlink when a cross-device
+rename fallback is triggered.
+
+Fix by replacing shutil.move() with os.replace() and creating the temp
+file in the same directory as the target to ensure atomic same-device
+rename. Also preserve the original file mode and avoid blindly following
+symlinks. Add follow_symlinks parameter to rewrite(), set_key(), and
+unset_key() to allow opting in to the old behavior when needed.
+
+Backported from upstream commit 790c5c02991100aa1bf41ee5330aca75edc51311
+to v1.1.0.
+
+CVE: CVE-2026-28684
+Upstream-Status: Backport [https://github.com/theskumar/python-dotenv/commit/790c5c02991100aa1bf41ee5330aca75edc51311]
+Signed-off-by: Bin Cao <bin.cao.cn@windriver.com>
+---
+ src/dotenv/cli.py  |  15 +++++-
+ src/dotenv/main.py |  72 ++++++++++++++++++++-----
+ tests/test_main.py | 129 +++++++++++++++++++++++++++++++++++++++++++++
+ 3 files changed, 201 insertions(+), 15 deletions(-)
+
+diff --git a/src/dotenv/cli.py b/src/dotenv/cli.py
+index 33ae148..259345b 100644
+--- a/src/dotenv/cli.py
++++ b/src/dotenv/cli.py
+@@ -93,7 +93,13 @@ def list(ctx: click.Context, format: bool) -> None:
+ @click.argument('key', required=True)
+ @click.argument('value', required=True)
+ def set(ctx: click.Context, key: Any, value: Any) -> None:
+-    """Store the given key/value."""
++    """
++    Store the given key/value.
++
++    This doesn't follow symlinks, to avoid accidentally modifying a file at a
++    potentially untrusted path.
++    """
++
+     file = ctx.obj['FILE']
+     quote = ctx.obj['QUOTE']
+     export = ctx.obj['EXPORT']
+@@ -125,7 +131,12 @@ def get(ctx: click.Context, key: Any) -> None:
+ @click.pass_context
+ @click.argument('key', required=True)
+ def unset(ctx: click.Context, key: Any) -> None:
+-    """Removes the given key."""
++    """
++    Removes the given key.
++
++    This doesn't follow symlinks, to avoid accidentally modifying a file at a
++    potentially untrusted path.
++    """
+     file = ctx.obj['FILE']
+     quote = ctx.obj['QUOTE']
+     success, key = unset_key(file, key, quote)
+diff --git a/src/dotenv/main.py b/src/dotenv/main.py
+index 1848d60..821bb9b 100644
+--- a/src/dotenv/main.py
++++ b/src/dotenv/main.py
+@@ -2,7 +2,7 @@ import io
+ import logging
+ import os
+ import pathlib
+-import shutil
++import stat
+ import sys
+ import tempfile
+ from collections import OrderedDict
+@@ -13,9 +13,7 @@ from .parser import Binding, parse_stream
+ from .variables import parse_variables
+ 
+ # A type alias for a string path to be used for the paths in this file.
+-# These paths may flow to `open()` and `shutil.move()`; `shutil.move()`
+-# only accepts string paths, not byte paths or file descriptors. See
+-# https://github.com/python/typeshed/pull/6832.
++# These paths may flow to `open()` and `os.replace()`.
+ StrPath = Union[str, "os.PathLike[str]"]
+ 
+ logger = logging.getLogger(__name__)
+@@ -131,21 +129,54 @@ def get_key(
+ def rewrite(
+     path: StrPath,
+     encoding: Optional[str],
++    follow_symlinks: bool = False,
+ ) -> Iterator[Tuple[IO[str], IO[str]]]:
+-    pathlib.Path(path).touch()
++    if follow_symlinks:
++        path = os.path.realpath(path)
+ 
+-    with tempfile.NamedTemporaryFile(mode="w", encoding=encoding, delete=False) as dest:
++    try:
++        source: IO[str] = open(path, encoding=encoding)
++        try:
++            path_stat = os.lstat(path)
++            original_mode: Optional[int] = (
++                stat.S_IMODE(path_stat.st_mode)
++                if stat.S_ISREG(path_stat.st_mode)
++                else None
++            )
++        except BaseException:
++            source.close()
++            raise
++    except FileNotFoundError:
++        source = io.StringIO("")
++        original_mode = None
++
++    with tempfile.NamedTemporaryFile(
++        mode="w",
++        encoding=encoding,
++        delete=False,
++        prefix=".tmp_",
++        dir=os.path.dirname(os.path.abspath(path)),
++    ) as dest:
++        dest_path = pathlib.Path(dest.name)
+         error = None
++
+         try:
+-            with open(path, encoding=encoding) as source:
++            with source:
+                 yield (source, dest)
+         except BaseException as err:
+             error = err
+ 
+     if error is None:
+-        shutil.move(dest.name, path)
++        try:
++            if original_mode is not None:
++                os.chmod(dest_path, original_mode)
++
++            os.replace(dest_path, path)
++        except BaseException:
++            dest_path.unlink(missing_ok=True)
++            raise
+     else:
+-        os.unlink(dest.name)
++        dest_path.unlink(missing_ok=True)
+         raise error from None
+ 
+ 
+@@ -156,12 +187,16 @@ def set_key(
+     quote_mode: str = "always",
+     export: bool = False,
+     encoding: Optional[str] = "utf-8",
++    follow_symlinks: bool = False,
+ ) -> Tuple[Optional[bool], str, str]:
+     """
+     Adds or Updates a key/value to the given .env
+ 
+-    If the .env path given doesn't exist, fails instead of risking creating
+-    an orphan .env somewhere in the filesystem
++    The target .env file is created if it doesn't exist.
++
++    This function doesn't follow symlinks by default, to avoid accidentally
++    modifying a file at a potentially untrusted path. If you don't need this
++    protection and need symlinks to be followed, use `follow_symlinks`.
+     """
+     if quote_mode not in ("always", "auto", "never"):
+         raise ValueError(f"Unknown quote_mode: {quote_mode}")
+@@ -179,7 +214,10 @@ def set_key(
+     else:
+         line_out = f"{key_to_set}={value_out}\n"
+ 
+-    with rewrite(dotenv_path, encoding=encoding) as (source, dest):
++    with rewrite(dotenv_path, encoding=encoding, follow_symlinks=follow_symlinks) as (
++        source,
++        dest,
++    ):
+         replaced = False
+         missing_newline = False
+         for mapping in with_warn_for_invalid_lines(parse_stream(source)):
+@@ -202,19 +240,27 @@ def unset_key(
+     key_to_unset: str,
+     quote_mode: str = "always",
+     encoding: Optional[str] = "utf-8",
++    follow_symlinks: bool = False,
+ ) -> Tuple[Optional[bool], str]:
+     """
+     Removes a given key from the given `.env` file.
+ 
+     If the .env path given doesn't exist, fails.
+     If the given key doesn't exist in the .env, fails.
++
++    This function doesn't follow symlinks by default, to avoid accidentally
++    modifying a file at a potentially untrusted path. If you don't need this
++    protection and need symlinks to be followed, use `follow_symlinks`.
+     """
+     if not os.path.exists(dotenv_path):
+         logger.warning("Can't delete from %s - it doesn't exist.", dotenv_path)
+         return None, key_to_unset
+ 
+     removed = False
+-    with rewrite(dotenv_path, encoding=encoding) as (source, dest):
++    with rewrite(dotenv_path, encoding=encoding, follow_symlinks=follow_symlinks) as (
++        source,
++        dest,
++    ):
+         for mapping in with_warn_for_invalid_lines(parse_stream(source)):
+             if mapping.key == key_to_unset:
+                 removed = True
+diff --git a/tests/test_main.py b/tests/test_main.py
+index 2d63eec..fbae934 100644
+--- a/tests/test_main.py
++++ b/tests/test_main.py
+@@ -1,6 +1,7 @@
+ import io
+ import logging
+ import os
++import stat
+ import sys
+ import textwrap
+ from unittest import mock
+@@ -61,6 +62,86 @@ def test_set_key_encoding(dotenv_path):
+     assert dotenv_path.read_text(encoding=encoding) == "a='é'\n"
+ 
+ 
++@pytest.mark.skipif(
++    sys.platform == "win32", reason="file mode bits behave differently on Windows"
++)
++def test_set_key_preserves_file_mode(dotenv_path):
++    dotenv_path.write_text("a=x\n")
++    dotenv_path.chmod(0o640)
++    mode_before = stat.S_IMODE(dotenv_path.stat().st_mode)
++
++    dotenv.set_key(dotenv_path, "a", "y")
++
++    mode_after = stat.S_IMODE(dotenv_path.stat().st_mode)
++    assert mode_before == mode_after
++
++
++def test_rewrite_closes_file_handle_on_lstat_failure(tmp_path):
++    dotenv_path = tmp_path / ".env"
++    dotenv_path.write_text("a=x\n")
++    real_open = open
++    opened_handles = []
++
++    def tracking_open(*args, **kwargs):
++        handle = real_open(*args, **kwargs)
++        opened_handles.append(handle)
++        return handle
++
++    with mock.patch("dotenv.main.os.lstat", side_effect=FileNotFoundError):
++        with mock.patch("dotenv.main.open", side_effect=tracking_open):
++            dotenv.set_key(dotenv_path, "a", "x")
++
++    assert opened_handles, "expected at least one file to be opened"
++    assert all(handle.closed for handle in opened_handles)
++
++
++@pytest.mark.skipif(
++    sys.platform == "win32", reason="symlinks require elevated privileges on Windows"
++)
++def test_set_key_symlink_to_existing_file(tmp_path):
++    target = tmp_path / "target.env"
++    target.write_text("a=x\n")
++    symlink = tmp_path / ".env"
++    symlink.symlink_to(target)
++
++    dotenv.set_key(symlink, "a", "y")
++
++    assert target.read_text() == "a=x\n"
++    assert not symlink.is_symlink()
++    assert "a='y'" in symlink.read_text()
++    assert stat.S_IMODE(symlink.stat().st_mode) == 0o600
++
++
++@pytest.mark.skipif(
++    sys.platform == "win32", reason="symlinks require elevated privileges on Windows"
++)
++def test_set_key_symlink_to_missing_file(tmp_path):
++    target = tmp_path / "nx"
++    symlink = tmp_path / ".env"
++    symlink.symlink_to(target)
++
++    dotenv.set_key(symlink, "a", "x")
++
++    assert not target.exists()
++    assert not symlink.is_symlink()
++    assert symlink.read_text() == "a='x'\n"
++
++
++@pytest.mark.skipif(
++    sys.platform == "win32", reason="symlinks require elevated privileges on Windows"
++)
++def test_set_key_follow_symlinks(tmp_path):
++    target = tmp_path / "target.env"
++    target.write_text("a=x\n")
++    symlink = tmp_path / ".env"
++    symlink.symlink_to(target)
++
++    dotenv.set_key(symlink, "a", "y", follow_symlinks=True)
++
++    assert target.read_text() == "a='y'\n"
++    assert symlink.is_symlink()
++
++
+ def test_set_key_permission_error(dotenv_path):
+     dotenv_path.chmod(0o000)
+ 
+@@ -188,6 +269,54 @@ def test_unset_non_existent_file(tmp_path):
+     )
+ 
+ 
++@pytest.mark.skipif(
++    sys.platform == "win32", reason="symlinks require elevated privileges on Windows"
++)
++def test_unset_key_symlink_to_existing_file(tmp_path):
++    target = tmp_path / "target.env"
++    target.write_text("a=x\n")
++    symlink = tmp_path / ".env"
++    symlink.symlink_to(target)
++
++    dotenv.unset_key(symlink, "a")
++
++    assert target.read_text() == "a=x\n"
++    assert not symlink.is_symlink()
++    assert symlink.read_text() == ""
++
++
++@pytest.mark.skipif(
++    sys.platform == "win32", reason="symlinks require elevated privileges on Windows"
++)
++def test_unset_key_symlink_to_missing_file(tmp_path):
++    target = tmp_path / "nx"
++    symlink = tmp_path / ".env"
++    symlink.symlink_to(target)
++    logger = logging.getLogger("dotenv.main")
++
++    with mock.patch.object(logger, "warning") as mock_warning:
++        result = dotenv.unset_key(symlink, "a")
++
++    assert result == (None, "a")
++    assert symlink.is_symlink()
++    mock_warning.assert_called_once()
++
++
++@pytest.mark.skipif(
++    sys.platform == "win32", reason="symlinks require elevated privileges on Windows"
++)
++def test_unset_key_follow_symlinks(tmp_path):
++    target = tmp_path / "target.env"
++    target.write_text("a=b\n")
++    symlink = tmp_path / ".env"
++    symlink.symlink_to(target)
++
++    dotenv.unset_key(symlink, "a", follow_symlinks=True)
++
++    assert target.read_text() == ""
++    assert symlink.is_symlink()
++
++
+ def prepare_file_hierarchy(path):
+     """
+     Create a temporary folder structure like the following:
+-- 
+2.43.0
+
diff --git a/recipes-devtools/python/python3-dotenv_1.1.0.bb b/recipes-devtools/python/python3-dotenv_1.1.0.bb
index 7e20a444..04c2c0b8 100644
--- a/recipes-devtools/python/python3-dotenv_1.1.0.bb
+++ b/recipes-devtools/python/python3-dotenv_1.1.0.bb
@@ -8,6 +8,7 @@ LIC_FILES_CHKSUM = "file://LICENSE;md5=e914cdb773ae44a732b392532d88f072"
 PYPI_PACKAGE = "python_dotenv"
 UPSTREAM_CHECK_PYPI_PACKAGE = "${PYPI_PACKAGE}"
 
+SRC_URI += "file://CVE-2026-28684.patch"
 SRC_URI[sha256sum] = "41f90bc6f5f177fb41f53e87666db362025010eb28f60a01c9143bfa33a2b2d5"
 
 inherit pypi setuptools3