CVE-2026-97554

/// Technical description

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

smb: client: avoid using uninitialized SIDs in cifs_posix_to_fattr()

cifs_posix_to_fattr() ignores the return value of posix_info_parse().

When a malformed POSIX directory entry is encountered (e.g. invalid

SID lengths from an untrusted server), posix_info_parse() returns -1

without populating the 'parsed' struct. The uninitialized stack

memory in parsed.owner and parsed.group is then passed to

sid_to_id(), which processes the garbage bytes and passes them to

request_key() to construct a SID string, potentially leaking kernel

stack contents to the userspace idmap daemon.

Fix this by checking the return value and skipping the SID-to-id

mapping when parsing fails. The remaining fattr fields (timestamps,

mode, etc.) are populated directly from the 'info' pointer so they

are unaffected.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References