CVE-2025-38527

Aliases:UBUNTU-CVE-2025-38527DEBIAN-CVE-2025-38527
Advisory lineage Upstream: 0 Downstream: 65
Modified
Published: 16 Aug 2025, 11:12
Last modified:05 Aug 2026, 12:02

Vulnerability Summary

Overall Risk (default)
high
70/100
CVSS Score
9.8 CRITICAL
v3.1 (cve.org)
EPSS Score
0.41% LOW
0% probability +0.40%
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

16 Aug 2025, 11:12
Published
Vulnerability first disclosed
05 Aug 2026, 12:02
Last Modified
Vulnerability information updated

Description

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix use-after-free in cifs_oplock_break A race condition can occur in cifs_oplock_break() leading to a use-after-free of the cinode structure when unmounting: cifs_oplock_break() _cifsFileInfo_put(cfile) cifsFileInfo_put_final() cifs_sb_deactive() [last ref, start releasing sb] kill_sb() kill_anon_super() generic_shutdown_super() evict_inodes() dispose_list() evict() destroy_inode() call_rcu(&inode->i_rcu, i_callback) spin_lock(&cinode->open_file_lock) <- OK [later] i_callback() cifs_free_inode() kmem_cache_free(cinode) spin_unlock(&cinode->open_file_lock) <- UAF cifs_done_oplock_break(cinode) <- UAF The issue occurs when umount has already released its reference to the superblock. When _cifsFileInfo_put() calls cifs_sb_deactive(), this releases the last reference, triggering the immediate cleanup of all inodes under RCU. However, cifs_oplock_break() continues to access the cinode after this point, resulting in use-after-free. Fix this by holding an extra reference to the superblock during the entire oplock break operation. This ensures that the superblock and its inodes remain valid until the oplock break completes.

CVSS Metrics

  • v3.1•HIGH•Score: 7.8CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
  • v3.1•CRITICAL•Score: 9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Trends

Current EPSS score: 0.41%• Percentile: 35%

Techniques & Countermeasures

  • CWE-416•Use After Free

    The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.

Affected Systems

  • debian•linux

    all | < 6.1.147-1 | < 6.12.41-1 | < 6.16.3-1

  • debian•linux-6.1

    < 6.1.153-1~deb11u1

  • ubuntu•linux

    all | < 5.15.0-163.173 | < 6.8.0-100.100

  • ubuntu•linux-allwinner-5.19

    all

  • ubuntu•linux-aws

    all | < 5.15.0-1097.104 | < 6.8.0-1046.49

  • ubuntu•linux-aws-5.0

    all

  • ubuntu•linux-aws-5.11

    all

  • ubuntu•linux-aws-5.13

    all

  • ubuntu•linux-aws-5.15

    < 5.15.0-1097.104~20.04.1

  • ubuntu•linux-aws-5.19

    all

  • ubuntu•linux-aws-5.3

    all

  • ubuntu•linux-aws-5.4

    all

  • ubuntu•linux-aws-5.8

    all

  • ubuntu•linux-aws-6.14

    < 6.14.0-1017.17~24.04.1

  • ubuntu•linux-aws-6.2

    all

  • ubuntu•linux-aws-6.5

    all

  • ubuntu•linux-aws-6.8

    < 6.8.0-1046.49~22.04.1

  • ubuntu•linux-aws-fips

    all | < 5.15.0-1097.104+fips1 | < 6.8.0-1046.49+fips1

  • ubuntu•linux-aws-hwe

    all

  • ubuntu•linux-azure

    all | all | < 5.15.0-1101.110 | < 6.8.0-1046.52

  • ubuntu•linux-azure-4.15

    all

  • ubuntu•linux-azure-5.11

    all

  • ubuntu•linux-azure-5.13

    all

  • ubuntu•linux-azure-5.15

    < 5.15.0-1102.111~20.04.1

  • ubuntu•linux-azure-5.19

    all

  • ubuntu•linux-azure-5.3

    all

  • ubuntu•linux-azure-5.4

    all

  • ubuntu•linux-azure-5.8

    all

  • ubuntu•linux-azure-6.11

    all

  • ubuntu•linux-azure-6.14

    < 6.14.0-1017.17~24.04.1

  • ubuntu•linux-azure-6.2

    all

  • ubuntu•linux-azure-6.5

    all

  • ubuntu•linux-azure-6.8

    < 6.8.0-1051.57~22.04.1

  • ubuntu•linux-azure-edge

    all

  • ubuntu•linux-azure-fde

    all | all | all | all

  • ubuntu•linux-azure-fde-5.19

    all

  • ubuntu•linux-azure-fde-6.14

    all

  • ubuntu•linux-azure-fde-6.2

    all

  • ubuntu•linux-azure-fde-6.8

    all

  • ubuntu•linux-azure-fips

    all | < 5.15.0-1101.110+fips1 | < 6.8.0-1046.52+fips1

  • ubuntu•linux-azure-nvidia

    all

  • ubuntu•linux-azure-nvidia-6.14

    all

  • ubuntu•linux-bluefield

    all | all | < 5.15.0-1081.83 | < 6.8.0-1016.20

  • ubuntu•linux-fips

    all | < 5.15.0-163.173+fips1 | < 6.8.0-100.100+fips1

  • ubuntu•linux-gcp

    all | all | < 5.15.0-1097.106 | < 6.8.0-1047.50

  • ubuntu•linux-gcp-4.15

    all

  • ubuntu•linux-gcp-5.11

    all

  • ubuntu•linux-gcp-5.13

    all

  • ubuntu•linux-gcp-5.15

    < 5.15.0-1097.106~20.04.1

  • ubuntu•linux-gcp-5.19

    all

Showing first 50 affected entries in server-rendered view.

References (42)