Bug 2541172 (CVE-2026-97561) - CVE-2026-97561 kernel: smb: client: honor forceuid/forcegid when mapping SIDs to uid/gid
Summary: CVE-2026-97561 kernel: smb: client: honor forceuid/forcegid when mapping SIDs...
Keywords:
Status: NEW
Alias: CVE-2026-97561
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-09-25 10:54 UTC by OSIDB Bzimport
Modified: 2026-09-29 03:02 UTC (History)
17 users (show)

Fixed In Version:
Clone Of:
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Description OSIDB Bzimport 2026-09-25 10:54:31 UTC
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.


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