CVE-2025-38527
What it is
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.
At a glance
- Exploitability
- Can be exploited over the network without logging in. High risk of data exposure, data tampering, service disruption.
- Exploit odds
- 0.5% chance of exploitation in the next 30 days (EPSS).
- Fix
- A patch, advisory or fixed version is referenced. Upgrade or apply it.
Timeline
- PublishedDisclosed publicly on CVE.org and NVD
- Last updatedMost recent change to the record
Why it ranks here
- Exploited in the wild: no, CISA does not list it.
- Exploit odds: 0.5% in the next 30 days (EPSS).
- Severity: 9.8 CRITICAL (CVSS).
- Fix: a patch or advisory is linked.
Details
- Published
- Last modified
- Exploit probability
- 0.5% · EPSS, next 30 days
- Weakness
- CWE-416 · Use after free
- Record status
- Modified
Affected
- Linux Kernel < 3.17
- Linux Kernel < 4.10
- Linux Kernel < 4.15
- Linux Kernel < 4.20
- Linux Kernel < 5.1
- Linux Kernel < 5.15.190
- Linux Kernel < 6.1.147
- Linux Kernel < 6.6.100
Attack profile CVSS 3.1 · 9.8
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Is it in your code?
Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.
Read https://cve-list.com/agent/cve/CVE-2025-38527.md and follow it. Check whether this project is affected by CVE-2025-38527. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.
Fix and advisories
- https://git.kernel.org/stable/c/09bce2138a30ef10d8821c8c3f73a4ab7a5726bc
- https://git.kernel.org/stable/c/0a4eec84d4d2c4085d4ed8630fd74e4b39033c1b
- https://git.kernel.org/stable/c/2baaf5bbab2ac474c4f92c10fcb3310f824db995
- https://git.kernel.org/stable/c/4256a483fe58af66a46cbf3dc48ff26e580d3308
- https://git.kernel.org/stable/c/705c79101ccf9edea5a00d761491a03ced314210
- https://git.kernel.org/stable/c/da11bd4b697b393a207f19a2ed7d382a811a3ddc
References
- https://git.kernel.org/stable/c/09bce2138a30ef10d8821c8c3f73a4ab7a5726bc
- https://git.kernel.org/stable/c/0a4eec84d4d2c4085d4ed8630fd74e4b39033c1b
- https://git.kernel.org/stable/c/2baaf5bbab2ac474c4f92c10fcb3310f824db995
- https://git.kernel.org/stable/c/4256a483fe58af66a46cbf3dc48ff26e580d3308
- https://git.kernel.org/stable/c/705c79101ccf9edea5a00d761491a03ced314210
- https://git.kernel.org/stable/c/da11bd4b697b393a207f19a2ed7d382a811a3ddc
- https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html