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Vulnerabilities

Vulnerability · CVE-2025-38527

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_brea…

Published Aug 16, 2025 · catalog updated Oct 15, 2026 · linux kernel

Check if you run it

No confirmed exploitation is on record for CVE-2025-38527. EPSS is 0.43%. Act only if a listed version of linux kernel is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High7.8
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.43%
Remediation
Advisory link
Affected products
cpe debian/debian linux · cpe linux/linux kernel

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) 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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe debian/debian linux11.0
  • cpe linux/linux kernelversion unspecified

How to fix CVE-2025-38527

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2025-38527. EPSS is 0.43%. Act only if a listed version of linux kernel is installed.

Which versions are affected?

Compare what you have installed with debian/debian linux 11.0. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-416: Use After Free. EPSS 0.43%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Aug 16, 2025 · NIST NVD

    Detected

    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_shut

  2. Oct 15, 2026 · NIST NVD

    Updated

    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_shut

Sources

  • CVE.orgVulnerability recordCVE-2025-38527

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2025-38527

    30-day exploitation probability 0.4%

    first.org
  • NIST NVDVulnerability recordCVE-2025-38527

    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() _cifsFileIn

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.