CVE-2026-3446

NameCVE-2026-3446
DescriptionWhen calling base64.b64decode() or related functions the decoding process would stop after encountering the first padded quad regardless of whether there was more information to be processed. This can lead to data being accepted which may be processed differently by other implementations. Use "validate=True" to enable stricter processing of base64 data.
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
pypy3 (PTS)bullseye7.3.5+dfsg-2+deb11u2vulnerable
bullseye (security)7.3.5+dfsg-2+deb11u5vulnerable
bookworm7.3.11+dfsg-2+deb12u3vulnerable
trixie7.3.19+dfsg-2vulnerable
sid, forky7.3.21+dfsg-4vulnerable
python2.7 (PTS)bullseye2.7.18-8+deb11u1vulnerable
python3.11 (PTS)bookworm3.11.2-6+deb12u6vulnerable
bookworm (security)3.11.2-6+deb12u3vulnerable
python3.13 (PTS)trixie3.13.5-2vulnerable
sid, forky3.13.12-1vulnerable
python3.14 (PTS)forky3.14.3-3vulnerable
sid3.14.4-1fixed
python3.9 (PTS)bullseye3.9.2-1vulnerable
bullseye (security)3.9.2-1+deb11u5vulnerable

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
pypy3source(unstable)(unfixed)
python2.7source(unstable)(unfixed)
python3.11source(unstable)(unfixed)
python3.13source(unstable)(unfixed)
python3.14source(unstable)3.14.4-1
python3.9source(unstable)(unfixed)

Notes

https://mail.python.org/archives/list/security-announce@python.org/thread/F5ZT5ICGJ6CKXVUJ34YBVY7WOZ5SHG53/
https://github.com/python/cpython/issues/145264
https://github.com/python/cpython/pull/145267
Fixed by: https://github.com/python/cpython/commit/4561f6418a691b3e89aef0901f53fe0dfb7f7c0e (v3.15.0a8)
Fixed by: https://github.com/python/cpython/commit/e31c55121620189a0d1a07b689762d8ca9c1b7fa (v3.14.4)
Fixed by: https://github.com/python/cpython/commit/1f9958f909c1b41a4ffc0b613ef8ec8fa5e7c474 (v3.13.13)

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