CVE-2026-74521: ksmbd: use memcmp() to compare ClientGUIDs
Greg Kroah-Hartman <[email protected]>
| Newsgroups | org.kernel.vger.linux-cve-announce |
|---|---|
| Message-ID | <2026081544-CVE-2026-74521-7ade@gregkh> |
From: Greg Kroah-Hartman <[email protected]> Description =========== In the Linux kernel, the following vulnerability has been resolved: ksmbd: use memcmp() to compare ClientGUIDs ClientGUID is a fixed-size binary value and can contain embedded NUL bytes. strncmp() stops comparing at the first NUL byte, so different ClientGUID values can incorrectly be treated as equal. Use memcmp() in SMB3 multichannel session binding and FSCTL_VALIDATE_NEGOTIATE_INFO to compare all SMB2_CLIENT_GUID_SIZE bytes. The Linux kernel CVE team has assigned CVE-2026-74521 to this issue. Affected and fixed versions =========================== Issue introduced in 5.15 with commit e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 and fixed in 7.1.8 with commit d535363299822c5caa543787b21bd5cfa3e41949 Issue introduced in 5.15 with commit e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 and fixed in 7.2-rc6 with commit e8bb506e6ef749ac0336f3e579d8d02396b7d832 Please see https://www.kernel.org for a full list of currently supported kernel versions by the kernel community. Unaffected versions might change over time as fixes are backported to older supported kernel versions. The official CVE entry at https://cve.org/CVERecord/?id=CVE-2026-74521 will be updated if fixes are backported, please check that for the most up to date information about this issue. Affected files ============== The file(s) affected by this issue are: fs/smb/server/smb2pdu.c Mitigation ========== The Linux kernel CVE team recommends that you update to the latest stable kernel version for this, and many other bugfixes. Individual changes are never tested alone, but rather are part of a larger kernel release. Cherry-picking individual commits is not recommended or supported by the Linux kernel community at all. If however, updating to the latest release is impossible, the individual changes to resolve this issue can be found at these commits: https://git.kernel.org/stable/c/d535363299822c5caa543787b21bd5cfa3e41949 https://git.kernel.org/stable/c/e8bb506e6ef749ac0336f3e579d8d02396b7d832