Linux Kernel up to 6.6.116/6.12.57/6.17.7 smb2_close_cached_fid use after free

CVSS Meta Temp Score
CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.
Current Exploit Price (≈)
Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.
CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
7.6$0-$5k0.00

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.6.116/6.12.57/6.17.7. It has been rated as critical. This impacts the function smb2_close_cached_fid. This manipulation causes use after free. This vulnerability is registered as CVE-2025-40328. No exploit is available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.6.116/6.12.57/6.17.7. It has been declared as critical. Affected by this vulnerability is the function smb2_close_cached_fid. The manipulation with an unknown input leads to a use after free vulnerability. The CWE definition for the vulnerability is CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix potential UAF in smb2_close_cached_fid() find_or_create_cached_dir() could grab a new reference after kref_put() had seen the refcount drop to zero but before cfid_list_lock is acquired in smb2_close_cached_fid(), leading to use-after-free. Switch to kref_put_lock() so cfid_release() is called with cfid_list_lock held, closing that gap.

It is possible to read the advisory at git.kernel.org. This vulnerability is known as CVE-2025-40328 since 04/16/2025. The exploitation appears to be easy. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 01/27/2026).

The vulnerability scanner Nessus provides a plugin with the ID 296680 (SUSE SLES15 / openSUSE 15 Security Update : kernel (SUSE-SU-2026:0293-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.6.117, 6.12.58 or 6.17.8 eliminates this vulnerability. Applying the patch cb52d9c86d70298de0ab7c7953653898cbc0efd6/065bd62412271a2d734810dd50336cae88c54427/bdb596ceb4b7c3f28786a33840263728217fbcf5/734e99623c5b65bf2c03e35978a0b980ebc3c2f8 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at Tenable (296680). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.0
VulDB Meta Temp Score: 7.6

VulDB Base Score: 8.0
VulDB Temp Score: 7.6
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
💳💳💳💳💳💳
💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
UnlockUnlockUnlockUnlockUnlockUnlock
UnlockUnlockUnlockUnlockUnlockUnlock
UnlockUnlockUnlockUnlockUnlockUnlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Use after free
CWE: CWE-416 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

0-DayUnlockUnlockUnlockUnlock
TodayUnlockUnlockUnlockUnlock

Nessus ID: 296680
Nessus Name: SUSE SLES15 / openSUSE 15 Security Update : kernel (SUSE-SU-2026:0293-1)

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.6.117/6.12.58/6.17.8
Patch: cb52d9c86d70298de0ab7c7953653898cbc0efd6/065bd62412271a2d734810dd50336cae88c54427/bdb596ceb4b7c3f28786a33840263728217fbcf5/734e99623c5b65bf2c03e35978a0b980ebc3c2f8

Timelineinfo

04/16/2025 CVE reserved
12/09/2025 +237 days Advisory disclosed
12/09/2025 +0 days VulDB entry created
01/27/2026 +49 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2025-40328 (🔒)
GCVE (CVE): GCVE-0-2025-40328
GCVE (VulDB): GCVE-100-334915

Entryinfo

Created: 12/09/2025 07:45
Updated: 01/27/2026 16:23
Changes: 12/09/2025 07:45 (58), 01/27/2026 16:23 (2)
Complete: 🔍
Cache ID: 216:6F2:103

Discussion

No comments yet. Languages: en.

Please log in to comment.

◂ PreviousOverviewNext ▸

Might our Artificial Intelligence support you?

Check our Alexa App!