Is CVE-2025-38527 being actively exploited?

It is not currently in CISA's KEV catalog. Its EPSS exploitation probability is 0%.

What products does CVE-2025-38527 affect?

Tracked products affected include Debian, Linux Kernel. Check the version you run to see whether it is affected.

How do I fix CVE-2025-38527?

Apply the vendor fix promptly. An official patch or advisory is available. Upgrade affected products to a fixed version.

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CVE-2025-38527

Q: What is CVE-2025-38527?

CVE-2025-38527 is a critical-severity software vulnerability (Use-after-free) with a CVSS score of 9.8. 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

CRITICAL severity · CVSS 9.8 · Use-after-free

9.8CVSS CRITICAL

Summary

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.

Impact & exploitability

Attack vectorNetwork

Attack complexityLow

Privileges requiredNone

User interactionNone

Confidentiality impactHigh

Integrity impactHigh

Availability impactHigh

Exploit probability (EPSS)0%

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products we track (2)

Debian Linux Kernel

Recommendation

Apply the vendor fix promptly. Open any affected product above for its exact safe version.

Official patch: https://git.kernel.org/stable/c/09bce2138a30ef10d8821c8c3f73a4ab7a5726bc ↗

CVE-2025-38527

Summary

Impact & exploitability

Affected products we track (2)

Recommendation

Additional information