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Vulnerabilities

Vulnerability · CVE-2026-99256

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

Published Nov 3, 2026 · catalog updated Nov 7, 2026 · Linux Linux Kernel

Last checked Nov 7, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-99256. EPSS is 0.20%. Act only if a listed version of Linux Linux Kernel is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
Medium—
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.20%
Remediation
Advisory link
Affected products
Debian:12 linux · Debian:13 linux · Debian:14 linux · linux kernel · package unmanaged · vendor Linux Linux

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 , run: 'dmsetup suspend && dmsetup resume '. 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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • Debian:12 linux6.1.106-1, 6.1.106-2, 6.1.106-3
  • Debian:13 linux0 → 6.12.115-1
  • Debian:14 linux0 → 7.2.13-1
  • linux kernelversion unspecified
  • package unmanagedversion unspecified
  • vendor Linux Linuxversion unspecified

How to fix CVE-2026-99256

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-99256. EPSS is 0.20%. Act only if a listed version of Linux Linux Kernel is installed.

Which versions are affected?

Compare what you have installed with 6.1.106-1, 6.1.106-2, 6.1.106-3, 0 → 6.12.115-1, 0 → 7.2.13-1. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.20%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Debian security

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Nov 3, 2026 · Linux Kernel CVE

    Detected

    From: Greg Kroah-Hartman Description =========== 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

  2. Nov 3, 2026 · CVE.org

    Updated

    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 C

  3. Nov 7, 2026 · Trivy Vulnerability DB

    Fix available

    linux fixed in 6.12.115-1; linux fixed in 7.2.13-1

  4. Nov 7, 2026 · Trivy Vulnerability DB

    Fix available

    linux fixed in 6.12.115-1

  5. Nov 7, 2026 · Trivy Vulnerability DB

    Fix available

    linux fixed in 7.2.13-1

  6. Nov 7, 2026 · Trivy Vulnerability DB

    Updated

    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 C

Sources

  • CVE.orgVulnerability recordCVE-2026-99256

    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 l

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-99256

    30-day exploitation probability 0.20%

    first.org
  • Linux Kernel CVEVendor advisoryCVE-2026-99256

    From: Greg Kroah-Hartman Description =========== 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, b

    git.kernel.org
  • Snyk Vulnerability DatabasePackage advisorySNYK-UNMANAGED-TORVALDSLINUX-22182575

    Improper Locking

    security.snyk.io
  • Trivy Vulnerability DBPackage advisoryDEBIAN-CVE-2026-99256

    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 l

    osv.dev

References

Freshness

Last verified in this catalog Nov 7, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • FIRST EPSSNov 7, 2026
  • Trivy Vulnerability DBNov 7, 2026
  • Snyk Vulnerability DatabaseNov 6, 2026
  • Linux Kernel CVENov 4, 2026
  • CVE.orgNov 4, 2026