CVE-2026-97564

Description

In the Linux kernel, the following vulnerability has been resolved: smb: client: reject userspace cifs.idmap descriptions cifs.idmap key descriptions carry authority-bearing fields (owner and group SIDs and uid/gid values in "os:"/"gs:"/"oi:"/"gi:" form) that the cifs.idmap upcall helper treats as kernel-originating inputs. Unlike its sibling cifs.spnego, the cifs.idmap key type has no vet_description hook, so userspace can create keys of this type through request_key(2)/add_key(2) and supply those fields without CIFS origin. A request_key(2) call with a non-NULL callout then drives a root usermodehelper upcall (/sbin/request-key -> cifs.idmap) that consumes the unvetted description in root context. Only accept cifs.idmap descriptions while CIFS is using its private root_cred to request the key. id_to_sid()/sid_to_id() already run under override_creds(root_cred), so the kernel-originated path is unaffected. This mirrors commit 3da1fdf4efbc ("smb: client: reject userspace cifs.spnego descriptions"), which applied the same restriction to cifs.spnego.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

References

• https://git.kernel.org/stable/c/f29c1ec0e7d8c887a91df3f93bb4617c0ac95c6a ↗
• https://git.kernel.org/stable/c/17c93bcd17755523c21abb22cbf2a41a6eb0caaf ↗
• https://git.kernel.org/stable/c/e5964064e3fbe6325893408faff08ca33de0e2c3 ↗
• https://git.kernel.org/stable/c/96751028c0d4dec785709ea3eb0ab38a4f2ded96 ↗
• https://git.kernel.org/stable/c/1d3b24b16a0b013792e8f1e3ed060f0b46f537d1 ↗
• https://git.kernel.org/stable/c/d9d7eeb0cea5b55b82888f443622fd8d4ee064f3 ↗