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CVE-2026-99256

dm cache: fix issue with background work locking

CVSS score

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EPSS probability

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Risk score

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Published

3 h ago

OverviewPublic Exploits (0)NewsroomVulnerability Timeline
Patch status has not yet been verified

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Vulnerability description

DayBreach AI Explanation

Verified against sources

Linux Kernel dm cache Background Work Locking Issue

Sources read

1

Source agreement

Tam uyum

Evidence confidence

%55

Short explanation

A vulnerability has been identified in the Linux kernel dm cache subsystem related to background work locking. Caused by the use of rw_semaphore, this issue leads to lock ownership mismatches and kernel warnings.

Why does it matter?

This vulnerability can cause instability and kernel warnings within the dm cache subsystem. Such flaws in the locking mechanism impact the reliability of the affected component.

What should be done?

  • Follow vendor advisories and apply the relevant updates
Chain of evidence and sources2 verified claims

dm cache alt sistemi arka plan işlemleri için rw_semaphore yapısını kullanmaktaydı.

S0 · daybreach-canonicalS1 · cvelist

Kilitleme sorununu gidermek için rw_semaphore yerine spinlock ve bekleme kuyruğu tercih edilmiştir.

S0 · daybreach-canonicalS1 · cvelist
Show the technical text from the sources

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.

This explanation was compiled automatically from the source records. Scores, active exploitation, patch and exploit status come straight from the sources.

IMPACT: Affected Products and Software

Affected Products

The following products are affected by CVE-2026-99256 vulnerability. Where our threat engine knows the exact affected versions, they are listed below.

IDVENDORPRODUCTACTION
1linuxLinux View
2linuxLinux View
Total affected vendors: 1|Products: 2

RED HAT CSAF/VEX: Product Impact Check

Red Hat has not yet published a CSAF/VEX impact record for this CVE. This does not mean “not affected”.

SCORING: CVSS from Multiple Sources

CVSS Scores

The Common Vulnerability Scoring System is a standardised framework for assessing the severity of vulnerabilities in software and systems. We collect and display CVSS scores from several sources for each CVE.

SCOREVERSIONSEVERITYVECTORSOURCE
The sources have not yet published a verified CVSS metric.

Patch and Remediation Guide

Solution & Remediation Advisory

Patch status unknown

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Confirm the affected product and version against the source evidence above.
Restrict access to internet-facing services and apply network segmentation.
Until a patch is confirmed, follow the vendor advisory; do not read an unknown status as “no patch”.
Monitor server logs and network endpoints for signs of anomalous execution.

Public exploit and active exploitation status

Verified exploit intelligence

No verified public PoC, exploit repository or Metasploit module has been found for this CVE yet.

Weakness Classification and Attack Patterns (CWE & CAPEC)

CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorises the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-99256 is associated with the following CWEs:

CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')CWE-20: Improper Input Validation

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-99256 weaknesses.

CAPEC-66: SQL InjectionCAPEC-126: Path TraversalCAPEC-28: OS Command Injection

Official Sources and Advisories

https://git.kernel.org/stable/c/0c7a8cad7c96012a9157a189649e569d0390f384vendor-advisoryhttps://git.kernel.org/stable/c/f5db935d257023c3ef410bd39163b949b0e5a55dvendor-advisoryhttps://git.kernel.org/stable/c/6290507ecc0dd6dd40759729cbbbd49b1d2a63c4vendor-advisoryhttps://git.kernel.org/stable/c/8433fd005c25fd127021f67c9144a879fb585572vendor-advisoryhttps://git.kernel.org/stable/c/2f2cfa16dd0f4179bb988139dd37d00a42324f6cvendor-advisoryhttps://git.kernel.org/stable/c/73df2ff409f3db95029982fe3656329568e3715dvendor-advisoryhttps://git.kernel.org/stable/c/104f09e02038b0fc6bbb718b3976af029e15c1d0vendor-advisoryhttps://git.kernel.org/stable/c/bc9781c0247de107876f32929f1637db93a42b34vendor-advisory

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CVE-2026-99256 · dm cache: fix issue with background work…