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VulnerabilityPublished Updated

CVE-2026-63823: Linux kernel · keys: Pin request_key_auth payload in instantiate paths

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 7.8 High · fixed in fd15b457a86939c38aa12116adabd8ff686c5e51 : patch Linux kernel soon.

Data as of 26 Oct 2026, 13:47 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 5% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact
Total control over the software or total information disclosure

CISA SSVC assessment, 2026-10-16.

Patch
Available – fixed in fd15b457a86939c38aa12116adabd8ff686c5e51, f9b68632ac93cc742f2e411021c4dbfe452ea0c2, d8274181b0f28d450b42489723a5ba81042158d7 +5
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 19 Jul 2026

  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
LinuxLinuxAffected
  • ≥ b5f545c880a2a47947ba2118b2509644ab7a2969, < fd15b457a86939c38aa12116adabd8ff686c5e51
Fixed in
  • fd15b457a86939c38aa12116adabd8ff686c5e51
LinuxLinuxAffected
  • ≥ b5f545c880a2a47947ba2118b2509644ab7a2969, < f9b68632ac93cc742f2e411021c4dbfe452ea0c2
Fixed in
  • f9b68632ac93cc742f2e411021c4dbfe452ea0c2
LinuxLinuxAffected
  • ≥ b5f545c880a2a47947ba2118b2509644ab7a2969, < d8274181b0f28d450b42489723a5ba81042158d7
Fixed in
  • d8274181b0f28d450b42489723a5ba81042158d7
LinuxLinuxAffected
  • ≥ b5f545c880a2a47947ba2118b2509644ab7a2969, < 708709c65a1832a99b0eef8ae46e343ddaca3d06
Fixed in
  • 708709c65a1832a99b0eef8ae46e343ddaca3d06
LinuxLinuxAffected
  • ≥ b5f545c880a2a47947ba2118b2509644ab7a2969, < 7216ce8cb12fee44e309503955bb83806b106129
Fixed in
  • 7216ce8cb12fee44e309503955bb83806b106129
LinuxLinuxAffected
  • ≥ b5f545c880a2a47947ba2118b2509644ab7a2969, < 4982bfabce6b33b3c9eddb4fb900fe5568b7cf91
Fixed in
  • 4982bfabce6b33b3c9eddb4fb900fe5568b7cf91

Description

In the Linux kernel, the following vulnerability has been resolved: keys: Pin request_key_auth payload in instantiate paths A: request_key() B: KEYCTL_INSTANTIATE_IOV ================ ========================= create auth key store rka in auth key wait for helper get auth key load rka from auth key copy user payload sleep on #PF helper completed detach and free rka destroy auth key wake up use rka->target_key **USE-AFTER-FREE** Give request_key_auth payloads a refcount. Take a payload reference while authkey->sem stabilizes the payload and revocation state. Hold that reference across the instantiate and reject paths. Drop the auth key owning reference from revoke and destroy. [jarkko: Replaced the first two paragraphs of text with an actual concurrency scenario.]

References

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