Reference page — cumulative record through Wednesday, August 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.
Linux Linux — smb: client: fix use-after-free in cifs_oplock_break
AV AC PR UI S C I A CVSS EPSS %ile KEV
L L L N U H H H 7.8 .0040 33.9 —
AFFECTED
Product Versions Fixed
Linux b98749cac4a695f084a5ff076f4510b23e353ecd – —
Linux 5.1 – 5.15.190
TIMELINE
Apr 16 Reserved by Linux
Aug 16 Published (CNA: Linux)
Jul 30 RESCORED — CVE-2025-38527 (Linux). CVSS 9.8 → 7.8 (NVD).
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.
Lifecycle
Complete event history — 3 events, chronological
| Date | Event | Detail |
| April 16, 2025 | Reserved | Reserved by Linux |
| August 16, 2025 | Published | Published (CNA: Linux) |
| July 30, 2026 | RESCORED | RESCORED — CVE-2025-38527 (Linux). CVSS 9.8 → 7.8 (NVD). |
Affected
Affected products and packages — 2 rows
| Vendor | Product / Package | Ecosystem | Version introduced | Fixed |
| Linux | Linux | — | b98749cac4a695f084a5ff076f4510b23e353ecd | — |
| Linux | Linux | — | 5.1 | 5.15.190 |
About this page
This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2025-38527 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Wednesday, August 19, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.