---
id: CVE-2025-21887
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ovl: fix UAF in ovl_dentry_update_reval by moving dput() in ovl_link_up

  The issue was caused by dput(upper) being called before
  ovl_dentry_update_reval(), while upper-…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ovl: fix UAF in ovl_dentry_update_reval by moving dput() in ovl_link_up

  The issue was caused by dput(upper) being called before
  ovl_dentry_update_reval(), while upper-…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-416
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 5.10.188, < 5.11'
  - 'linux_kernel >= 5.15.121, < 5.15.179'
  - 'linux_kernel >= 6.1.39, < 6.1.130'
  - 'linux_kernel >= 6.3.13, < 6.4'
  - 'linux_kernel >= 6.4.4, < 6.6.81'
  - 'linux_kernel >= 6.7, < 6.12.18'
  - 'linux_kernel >= 6.13, < 6.13.6'
  - linux_kernel = 6.14
patched:
  - linux_kernel 6.13.6
published: '2025-03-27'
updated: '2026-07-14'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-21887'
references:
  - url: 'https://git.kernel.org/stable/c/3594aad97e7be2557ca9fa9c931b206b604028c8'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/4b49d939b5a79117f939b77cc67efae2694d9799'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/60b4b5c1277fc491da9e1e7abab307bfa39c2db7'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/64455c8051c3aedc71abb7ec8d47c80301f99f00'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a7c41830ffcd17b2177a95a9b99b270302090c35'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/c84e125fff2615b4d9c259e762596134eddd2f27'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/f77618291836168eca99e89cd175256f928f5e64'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-019113.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
  - cve.org
epss: 0.00213
epssPercentile: 0.10259
ingestedAt: '2026-07-14T13:36:56.015Z'
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2025-03-27T16:59:58.510815Z'
---

## Overview

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

ovl: fix UAF in ovl_dentry_update_reval by moving dput() in ovl_link_up

The issue was caused by dput(upper) being called before
ovl_dentry_update_reval(), while upper->d_flags was still
accessed in ovl_dentry_remote().

Move dput(upper) after its last use to prevent use-after-free.

BUG: KASAN: slab-use-after-free in ovl_dentry_remote fs/overlayfs/util.c:162 [inline]
BUG: KASAN: slab-use-after-free in ovl_dentry_update_reval+0xd2/0xf0 fs/overlayfs/util.c:167

Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:114
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0xc3/0x620 mm/kasan/report.c:488
 kasan_report+0xd9/0x110 mm/kasan/report.c:601
 ovl_dentry_remote fs/overlayfs/util.c:162 [inline]
 ovl_dentry_update_reval+0xd2/0xf0 fs/overlayfs/util.c:167
 ovl_link_up fs/overlayfs/copy_up.c:610 [inline]
 ovl_copy_up_one+0x2105/0x3490 fs/overlayfs/copy_up.c:1170
 ovl_copy_up_flags+0x18d/0x200 fs/overlayfs/copy_up.c:1223
 ovl_rename+0x39e/0x18c0 fs/overlayfs/dir.c:1136
 vfs_rename+0xf84/0x20a0 fs/namei.c:4893
...
 </TASK>

## Affected

- `linux_kernel >= 5.10.188, < 5.11`
- `linux_kernel >= 5.15.121, < 5.15.179`
- `linux_kernel >= 6.1.39, < 6.1.130`
- `linux_kernel >= 6.3.13, < 6.4`
- `linux_kernel >= 6.4.4, < 6.6.81`
- `linux_kernel >= 6.7, < 6.12.18`
- `linux_kernel >= 6.13, < 6.13.6`
- `linux_kernel = 6.14`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.13.6`