---
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: medium
cvss: 5.5
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-908
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    c9a8b60ce140a68d172452f418137fc7ddbae7db
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    da6e25842431982d5a53cf00d925b98c690f4467
  - Linux < 7.2.7
  - Linux (all versions)
published: '2026-09-25'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T11:18:08.807'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-97554'
references:
  - url: 'https://git.kernel.org/stable/c/2be31f252ade791b84f7164991f14436aed1d4b9'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - 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
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-97554.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-97554'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2541276'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-97554'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-97554'
  - url: >-
      https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-97554.mbox
  - url: 'https://git.kernel.org/stable/c/604feb3e8141bf11f5afd48d36d401fee5af9536'
  - url: 'https://git.kernel.org/stable/c/33106019c3be57b5fc6411cfaad6d98214a51265'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
epss: 0.00206
epssPercentile: 0.10583
cvssSource: vendor
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.

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-10-17 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-97554.json)