Linux Kernel up to 7.2.12 dm cache cache_resume locking

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.
7.4	$0-$5k	0.00

Summaryinfo

A vulnerability classified as critical was found in Linux Kernel up to 7.2.12. This affects the function cache_resume of the component dm cache. Executing a manipulation can lead to locking. The identification of this vulnerability is CVE-2026-99256. The attack can only be executed locally. There is no exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Linux Kernel up to 7.2.12. It has been declared as critical. This vulnerability affects the function cache_resume of the component dm cache. The manipulation with an unknown input leads to a locking vulnerability. The CWE definition for the vulnerability is CWE-667. The product does not properly acquire or release a lock on a resource, leading to unexpected resource state changes and behaviors. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: dm cache: fix issue with background work locking dm cache used a rw_semaphore for background_work_lock. Write locks on rw_semaphores have strict owner semantics, but there was no guarantee that the process that locked background_work_lock was the same process that unlocked it. This can be easily seen using a kernel compiled with CONFIG_DEBUG_RWSEMS. Given a dm cache device <cache>, run: 'dmsetup suspend <cache> && dmsetup resume <cache>'. This will trigger a kernel warning: DEBUG_RWSEMS_WARN_ON((rwsem_owner(sem) != current) && !rwsem_test_oflags(sem, RWSEM_NONSPINNABLE)) triggered by cache_resume(). To fix this, switch from a rw_semaphore to a spinlock and a wait queue. dm cache already has a wait queue and associated counter, migration_wait and nr_allocated_migrations, that was getting woken up when background work was getting completed, but wasn't actually used by anything. This is replaced by the background_work queue and counter.

The advisory is available at git.kernel.org. This vulnerability was named CVE-2026-99256 since 09/25/2026. The exploitation appears to be easy. Local access is required to approach this attack. Additional levels of successful authentication are needed for exploitation. Successful exploitation requires user interaction by the victim. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 11/04/2026).

The vulnerability scanner Nessus provides a plugin with the ID 375609 (Linux Distros Unpatched Vulnerability : CVE-2026-99256), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.10.273, 5.15.224, 6.1.191, 6.6.161, 6.12.115, 6.18.59 or 7.2.13 eliminates this vulnerability. Applying the patch 0c7a8cad7c96012a9157a189649e569d0390f384/f5db935d257023c3ef410bd39163b949b0e5a55d/6290507ecc0dd6dd40759729cbbbd49b1d2a63c4/8433fd005c25fd127021f67c9144a879fb585572/2f2cfa16dd0f4179bb988139dd37d00a42324f6c/73df2ff409f3db95029982fe3656329568e3715d/104f09e02038b0fc6bbb718b3976af029e15c1d0/bc9781c0247de107876f32929f1637db93a42b34 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at Tenable (375609). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 5.10.272
• 5.15.223
• 6.1.190
• 6.6.160
• 6.12.114
• 6.18.0
• 6.18.1
• 6.18.2
• 6.18.3
• 6.18.4
• 6.18.5
• 6.18.6
• 6.18.7
• 6.18.8
• 6.18.9
• 6.18.10
• 6.18.11
• 6.18.12
• 6.18.13
• 6.18.14
• 6.18.15
• 6.18.16
• 6.18.17
• 6.18.18
• 6.18.19
• 6.18.20
• 6.18.21
• 6.18.22
• 6.18.23
• 6.18.24
• 6.18.25
• 6.18.26
• 6.18.27
• 6.18.28
• 6.18.29
• 6.18.30
• 6.18.31
• 6.18.32
• 6.18.33
• 6.18.34
• 6.18.35
• 6.18.36
• 6.18.37
• 6.18.38
• 6.18.39
• 6.18.40
• 6.18.41
• 6.18.42
• 6.18.43
• 6.18.44
• 6.18.45
• 6.18.46
• 6.18.47
• 6.18.48
• 6.18.49
• 6.18.50
• 6.18.51
• 6.18.52
• 6.18.53
• 6.18.54
• 6.18.55
• 6.18.56
• 6.18.57
• 6.18.58
• 7.2.0
• 7.2.1
• 7.2.2
• 7.2.3
• 7.2.4
• 7.2.5
• 7.2.6
• 7.2.7
• 7.2.8
• 7.2.9
• 7.2.10
• 7.2.11
• 7.2.12

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.7
VulDB Meta Temp Score: 7.4

VulDB Base Score: 7.7
VulDB Temp Score: 7.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

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

Exploitinginfo

Class: Locking
CWE: CWE-667
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: Partially

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Nessus ID: 375609
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-99256

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.10.273/5.15.224/6.1.191/6.6.161/6.12.115/6.18.59/7.2.13
Patch: 0c7a8cad7c96012a9157a189649e569d0390f384/f5db935d257023c3ef410bd39163b949b0e5a55d/6290507ecc0dd6dd40759729cbbbd49b1d2a63c4/8433fd005c25fd127021f67c9144a879fb585572/2f2cfa16dd0f4179bb988139dd37d00a42324f6c/73df2ff409f3db95029982fe3656329568e3715d/104f09e02038b0fc6bbb718b3976af029e15c1d0/bc9781c0247de107876f32929f1637db93a42b34

Timelineinfo

09/25/2026 CVE reserved
11/03/2026 +39 days Advisory disclosed
11/03/2026 +0 days VulDB entry created
11/04/2026 +1 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CNA: Linux
CVE: CVE-2026-99256 (🔒)

GCVE (CVE): GCVE-0-2026-99256
GCVE (VulDB): GCVE-100-430234

Entryinfo

Created: 11/03/2026 12:43
Updated: 11/04/2026 03:36
Changes: 11/03/2026 12:43 (59), 11/04/2026 03:36 (2)
Complete: 🔍
Cache ID: 216::103

If you want to get best quality of vulnerability data, you may have to visit VulDB.

Discussion

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