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VulnerabilityPublished Updated

CVE-2025-40022: Linux kernel · crypto: af_alg – Fix incorrect boolean values in af_alg_ctx

Affects Linux kernelSource GCVE Database

0

Not known to be exploited · fixed in 6.17.0-6.6 : update Linux kernel when convenient.

Data as of 26 Oct 2026, 11:07 UTC

Severity
Medium

Rated by Threat Radar · No CVSS score from NVD or the CNA

EPSS
0.2% chance of exploitation in 30 days – higher than 14% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 6.17.0-6.6, 6.17.0-1003.3, 6.17.0-1006.6 +3
CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 24 Oct 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: 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 26 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
Ubuntu 25.10linuxpkg:deb/ubuntu/linux?arch=source&distro=questingOther threatsAffected
  • <6.17.0-6.6
Fixed in
  • 6.17.0-6.6
Ubuntu 25.10linux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=questingOther threatsAffected
  • <6.17.0-1003.3
Fixed in
  • 6.17.0-1003.3
Ubuntu 25.10linux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=questingOther threatsAffected
  • <6.17.0-1006.6
Fixed in
  • 6.17.0-1006.6
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=questingOther threatsAffected
  • 6.17.0-1003.3 – 6.17.0-1017.17
10 affected builds
Fixed in–
Ubuntu 25.10linux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=questingOther threatsAffected
  • <6.17.0-1003.3
Fixed in
  • 6.17.0-1003.3
Ubuntu 25.10linux-oraclepkg:deb/ubuntu/linux-oracle?arch=source&distro=questingOther threatsAffected
  • <6.17.0-1003.3
Fixed in
  • 6.17.0-1003.3

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

Description

In the Linux kernel, the following vulnerability has been resolved: crypto: af_alg - Fix incorrect boolean values in af_alg_ctx Commit 1b34cbbf4f01 ("crypto: af_alg - Disallow concurrent writes in af_alg_sendmsg") changed some fields from bool to 1-bit bitfields of type u32. However, some assignments to these fields, specifically 'more' and 'merge', assign values greater than 1. These relied on C's implicit conversion to bool, such that zero becomes false and nonzero becomes true. With a 1-bit bitfields of type u32 instead, mod 2 of the value is taken instead, resulting in 0 being assigned in some cases when 1 was intended. Fix this by restoring the bool type.

References

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