CVE-2026-31637: Linux kernel · rxrpc: reject undecryptable rxkad response tickets
Affects Linux kernelSource CVE Database V5
Not known to be exploited · CVSS 9.8 Critical · fixed in fe4447cd95623b1cfacc15f280aab73a6d7340b2 : patch Linux kernel as a priority.
Data as of 26 Oct 2026, 12:55 UTC
- EPSS
- 0.5% chance of exploitation in 30 days – higher than 47% 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 can 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 fe4447cd95623b1cfacc15f280aab73a6d7340b2, b3a808cd0790b5075aaa2bc3588edf02cd71d352, a149dcae23309df9de1c3b6b5d468610ef5ab7de +5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 24 Apr 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: rxrpc: reject undecryptable rxkad response tickets rxkad_decrypt_ticket() decrypts the RXKAD response ticket and then parses the buffer as plaintext without checking whether crypto_skcipher_decrypt() succeeded. A malformed RESPONSE can therefore use a non-block-aligned ticket length, make the decrypt operation fail, and still drive the ticket parser with attacker-controlled bytes. Check the decrypt result and abort the connection with RXKADBADTICKET when ticket decryption fails.
References
- git.kernel.org/stable/c/252157d939d179b5d767cb860ff8fa7f8723b67a (opens in a new tab)
- git.kernel.org/stable/c/a75b3b361dd481d942c5f259a82d59718a41092c (opens in a new tab)
- git.kernel.org/stable/c/b3a808cd0790b5075aaa2bc3588edf02cd71d352 (opens in a new tab)
- git.kernel.org/stable/c/47073aab8a3a5a7b41c9bd37d2a3dcbeeccd6c8a (opens in a new tab)
- git.kernel.org/stable/c/a149dcae23309df9de1c3b6b5d468610ef5ab7de (opens in a new tab)
- git.kernel.org/stable/c/22f6258e7b31dba9bf88dce4e3ee7f0f20072e60 (opens in a new tab)
- git.kernel.org/stable/c/58fcd1b156152613ba00a064a129fb69507ddd7d (opens in a new tab)
- git.kernel.org/stable/c/fe4447cd95623b1cfacc15f280aab73a6d7340b2 (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-784472.html (opens in a new tab)