CVE-2026-97561

Summary

In the Linux kernel, the following vulnerability has been resolved:

smb: client: honor forceuid/forcegid when mapping SIDs to uid/gid

When the administrator mounts with forceuid or forcegid (uid=/gid= mount options), they expect all files to appear owned by the specified user/group. However, several code paths unconditionally called sid_to_id() to overwrite cf_uid/cf_gid with server-provided values, ignoring the administrator's explicit override:

  • smb311_posix_info_to_fattr() (stat via POSIX extensions)
  • cifs_posix_to_fattr() (readdir via POSIX extensions)
  • parse_sec_desc() (CIFS ACL ownership mapping)

This allowed an untrusted server to dictate local file ownership even when the mount was configured to force specific uid/gid values.

Fix all three call sites to check CIFS_MOUNT_OVERR_UID and CIFS_MOUNT_OVERR_GID before calling sid_to_id(), following the same pattern already used by cifs_unix_basic_to_fattr() for unix extensions.

Affected Software

VendorProductVersion RangeStatus
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < e1b74f8f8c1d13190b09fe623b729d36b7ac22a8affected
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 18a72975e9f35aadecc75b031f693f2d1f49308faffected
LinuxLinux0 < 7.2.7affected
LinuxLinux7.2.7 <= 7.2.*unaffected
LinuxLinux7.3-rc3 <= *unaffected

Weaknesses

References