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VulnerabilityPublished Updated

CVE-2024-26957: Linux kernel · s390/zcrypt: fix reference counting on zcrypt card objects

Affects Linux kernelSource GCVE Database

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Not known to be exploited · CVSS 7.8 High · fixed in 5.4.0-1128.138~18.04.1 : patch Linux kernel soon.

Data as of 6 Nov 2026, 15:18 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 5.4.0-1128.138~18.04.1, 5.4.0-1133.140~18.04.1, 5.4.0-1132.141~18.04.1 +62
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 1 May 2024

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 6 Nov 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
Ubuntu 24.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-35.35
Fixed in
  • 6.8.0-35.35
Ubuntu 24.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-1009.9
Fixed in
  • 6.8.0-1009.9
Ubuntu 24.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-1008.8
Fixed in
  • 6.8.0-1008.8
Ubuntu 24.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-1008.9
Fixed in
  • 6.8.0-1008.9
Ubuntu 24.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-1004.7
Fixed in
  • 6.8.0-1004.7
Ubuntu 24.04 LTSlinux-ibmpkg:deb/ubuntu/linux-ibm?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-1006.6
Fixed in
  • 6.8.0-1006.6

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A patch fixing the reference counting issue on zcrypt card objects is available and included in several Linux kernel versions. Users should upgrade to one of the fixed versions listed by the vendor to remediate this vulnerability. No additional mitigation steps are indicated beyond applying the official kernel updates.

Description

A use-after-free vulnerability was discovered in the Linux kernel's s390/zcrypt subsystem due to incorrect reference counting on zcrypt card objects. This flaw could lead to the premature freeing of zcrypt card objects while still in use, causing potential system instability or crashes. The issue was identified during tests involving hot-plugging crypto cards on KVM guests with debug kernel builds. The vulnerability has been addressed in multiple fixed Linux kernel versions.

References

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