CVE-2025-38527: Linux azure · 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
Affects linux-azureSource GCVE Database
Mentioned vulnerabilities
Not known to be exploited · CVSS 9.8 Low · patch available : update linux-azure when convenient.
Data as of 25 Oct 2026, 19:02 UTC
- EPSS
- 0.4% chance of exploitation in 30 days – higher than 37% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 16 Aug 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Red Hatredhat/kernel-rtpkg:rpm/redhat/kernel-rtOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Red Hat has released updated kernel-rt packages that address these vulnerabilities. Users of affected Red Hat Enterprise Linux for Real Time 8 variants should apply the security update as detailed in the Red Hat advisory RHSA-2025:17398 and reboot their systems to ensure the fixes take effect. No additional mitigation steps are indicated or required beyond applying the official update and rebooting.
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.
References
- access.redhat.com/errata/RHSA-2025:17398 (opens in a new tab)
- access.redhat.com/security/updates/classification/ (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2388928 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2393731 (opens in a new tab)
- security.access.redhat.com/data/csaf/v2/advisories/2025/rhsa-2025_17398.json (opens in a new tab)
- ubuntu.com/security/CVE-2025-38527 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2025-38527 (opens in a new tab)
- git.kernel.org/linus/705c79101ccf9edea5a00d761491a03ced314210 (opens in a new tab)
- git.kernel.org/stable/c/09bce2138a30ef10d8821c8c3f73a4ab7a5726bc (opens in a new tab)
- git.kernel.org/stable/c/0a4eec84d4d2c4085d4ed8630fd74e4b39033c1b (opens in a new tab)
- git.kernel.org/stable/c/2baaf5bbab2ac474c4f92c10fcb3310f824db995 (opens in a new tab)
- git.kernel.org/stable/c/705c79101ccf9edea5a00d761491a03ced314210 (opens in a new tab)
- git.kernel.org/stable/c/da11bd4b697b393a207f19a2ed7d382a811a3ddc (opens in a new tab)
- ubuntu.com/security/notices/USN-7879-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7879-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7880-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7879-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-7909-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7879-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-7909-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7909-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-7910-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7909-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-7910-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7933-1 (opens in a new tab)