What is CVE-2025-40320?

CVE-2025-40320 is a Critical severity Linux kernel vulnerability with a CVSS score of 9.8 out of 10, affecting Linux kernel versions from 6.6.32 onward and patched in 6.6.117, 6.12.58, 6.17.8 and others. CVE-2025-40320 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2025-40320?

CVE-2025-40320 has a CVSS score of 9.8 out of 10, rated Critical severity. The vector string is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

Is there a patch available for CVE-2025-40320?

Yes, CVE-2025-40320 has been patched. Fixed versions include 6.6.117, 6.12.58, 6.17.8 and others. If you are running Linux kernel 6.6.32 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2025-40320 actively exploited?

CVE-2025-40320 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

CVE-2025-40320

Critical

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix potential cfid UAF in smb2_query_info_compound When smb2_query_info_compound() retries, a previously allocated cfid may have been freed in the first attempt. Because cfid wasn't reset on replay, later cleanup could act on a stale pointer, leading to a potential use-after-free. Reinitialize cfid to NULL under the replay label. Example trace (trimmed): refcount_t: underflow; use-after-free. WARNING: CPU: 1 PID: 11224 at ../lib/refcount.c:28 refcount_warn_saturate+0x9c/0x110 [...] RIP: 0010:refcount_warn_saturate+0x9c/0x110 [...] Call Trace: <TASK> smb2_query_info_compound+0x29c/0x5c0 [cifs f90b72658819bd21c94769b6a652029a07a7172f] ? step_into+0x10d/0x690 ? __legitimize_path+0x28/0x60 smb2_queryfs+0x6a/0xf0 [cifs f90b72658819bd21c94769b6a652029a07a7172f] smb311_queryfs+0x12d/0x140 [cifs f90b72658819bd21c94769b6a652029a07a7172f] ? kmem_cache_alloc+0x18a/0x340 ? getname_flags+0x46/0x1e0 cifs_statfs+0x9f/0x2b0 [cifs f90b72658819bd21c94769b6a652029a07a7172f] statfs_by_dentry+0x67/0x90 vfs_statfs+0x16/0xd0 user_statfs+0x54/0xa0 __do_sys_statfs+0x20/0x50 do_syscall_64+0x58/0x80

Package Linux Kernel

Published 2025-12-08

Last modified 2026-07-30

CVSS version 3.1

Patch available

Yes

CVSS 3.1 score

9.8

out of 10

Critical

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Vector string

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

Affected versions

Linux kernel versions 6.6.32, 6.8 and later are affected. Fixed in 6.6.117, 6.12.58, 6.17.8, 6.18 and their respective stable series.

Affected from

≥ 6.6.32 ≥ 6.8

Fixed in

✓ 6.6.117 6.6.x ✓ 6.12.58 6.12.x ✓ 6.17.8 6.17.x ✓ 6.18

References

4 total

Details

CVE ID CVE-2025-40320

Severity Critical

CVSS score 9.8 / 10

CVSS version 3.1

Published 2025-12-08

Modified 2026-07-30

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2025-40320?

CVE-2025-40320 is a Critical severity Linux kernel vulnerability with a CVSS score of 9.8 out of 10 . It affects Linux kernel versions from 6.6.32 onward and has been patched in 6.6.117, 6.12.58, 6.17.8 and others. CVE-2025-40320 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2025-40320?

CVE-2025-40320 has a CVSS score of 9.8 out of 10, rated Critical severity (CVSS 3.1). The vector string is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
Is there a patch available for CVE-2025-40320?

Yes. CVE-2025-40320 has been patched. Fixed versions include 6.6.117, 6.12.58, 6.17.8 and others. If you are running Linux kernel 6.6.32 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2025-40320 actively exploited?

No. CVE-2025-40320 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.