CVE-2026-31476

NameCVE-2026-31476
DescriptionIn the Linux kernel, the following vulnerability has been resolved: ksmbd: do not expire session on binding failure When a multichannel session binding request fails (e.g. wrong password), the error path unconditionally sets sess->state = SMB2_SESSION_EXPIRED. However, during binding, sess points to the target session looked up via ksmbd_session_lookup_slowpath() -- which belongs to another connection's user. This allows a remote attacker to invalidate any active session by simply sending a binding request with a wrong password (DoS). Fix this by skipping session expiration when the failed request was a binding attempt, since the session does not belong to the current connection. The reference taken by ksmbd_session_lookup_slowpath() is still correctly released via ksmbd_user_session_put().
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)
ReferencesDLA-4561-1, DSA-6238-1, DSA-6243-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
linux (PTS)bullseye5.10.223-1fixed
bullseye (security)5.10.251-4fixed
bookworm6.1.159-1vulnerable
bookworm (security)6.1.170-3fixed
trixie6.12.73-1vulnerable
trixie (security)6.12.86-1fixed
forky, sid7.0.4-1fixed
linux-6.1 (PTS)bullseye (security)6.1.170-3~deb11u1fixed

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

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
linuxsourcebullseye(not affected)
linuxsourcebookworm6.1.170-1DSA-6243-1
linuxsourcetrixie6.12.85-1DSA-6238-1
linuxsource(unstable)6.19.11-1
linux-6.1sourcebullseye6.1.170-1~deb11u1DLA-4561-1

Notes

[bullseye] - linux <not-affected> (Vulnerable code not present)
https://git.kernel.org/linus/9bbb19d21ded7d78645506f20d8c44895e3d0fb9 (7.0-rc6)

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