---
id: CVE-2026-97554
title: |-
  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 direc…
summary: |-
  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 direc…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    c9a8b60ce140a68d172452f418137fc7ddbae7db
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    da6e25842431982d5a53cf00d925b98c690f4467
  - Linux < 7.2.7
  - Linux (all versions)
published: '2026-09-25'
updated: '2026-09-25'
sourceUpdated: '2026-09-25T11:17:05.860'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-97554'
references:
  - url: 'https://git.kernel.org/stable/c/c9a8b60ce140a68d172452f418137fc7ddbae7db'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/da6e25842431982d5a53cf00d925b98c690f4467'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-25T11:06:38.917Z'
---

## Overview

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

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.