CVE-2026-63823: Linux kernel · keys: Pin request_key_auth payload in instantiate paths
Affects Linux kernelSource CVE Database V5
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
- 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:HExploitation evidence
Disclosed: evidence found.
CVE published 19 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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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
- git.kernel.org/stable/c/d8274181b0f28d450b42489723a5ba81042158d7 (opens in a new tab)
- git.kernel.org/stable/c/4982bfabce6b33b3c9eddb4fb900fe5568b7cf91 (opens in a new tab)
- git.kernel.org/stable/c/708709c65a1832a99b0eef8ae46e343ddaca3d06 (opens in a new tab)
- git.kernel.org/stable/c/35ab4db86774d82389e4b9559e26ab7f68d8e395 (opens in a new tab)
- git.kernel.org/stable/c/f9b68632ac93cc742f2e411021c4dbfe452ea0c2 (opens in a new tab)
- git.kernel.org/stable/c/7216ce8cb12fee44e309503955bb83806b106129 (opens in a new tab)
- git.kernel.org/stable/c/83c0a1cb296d955d5f4d1f0bd8a769ba8ed8c29f (opens in a new tab)
- git.kernel.org/stable/c/fd15b457a86939c38aa12116adabd8ff686c5e51 (opens in a new tab)