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VulnerabilityPublished Updated

CVE-2026-31637: Linux kernel · rxrpc: reject undecryptable rxkad response tickets

Affects Linux kernelSource CVE Database V5

0

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

CVSS 3.1 base score
9.8Critical
How severe the flaw is on the 0–10 CVSS scale.
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:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 24 Apr 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
  • ≥ 17926a79320afa9b95df6b977b40cca6d8713cea, < fe4447cd95623b1cfacc15f280aab73a6d7340b2
Fixed in
  • fe4447cd95623b1cfacc15f280aab73a6d7340b2
LinuxLinuxAffected
  • ≥ 17926a79320afa9b95df6b977b40cca6d8713cea, < b3a808cd0790b5075aaa2bc3588edf02cd71d352
Fixed in
  • b3a808cd0790b5075aaa2bc3588edf02cd71d352
LinuxLinuxAffected
  • ≥ 17926a79320afa9b95df6b977b40cca6d8713cea, < a149dcae23309df9de1c3b6b5d468610ef5ab7de
Fixed in
  • a149dcae23309df9de1c3b6b5d468610ef5ab7de
LinuxLinuxAffected
  • ≥ 17926a79320afa9b95df6b977b40cca6d8713cea, < a75b3b361dd481d942c5f259a82d59718a41092c
Fixed in
  • a75b3b361dd481d942c5f259a82d59718a41092c
LinuxLinuxAffected
  • ≥ 17926a79320afa9b95df6b977b40cca6d8713cea, < 252157d939d179b5d767cb860ff8fa7f8723b67a
Fixed in
  • 252157d939d179b5d767cb860ff8fa7f8723b67a
LinuxLinuxAffected
  • ≥ 17926a79320afa9b95df6b977b40cca6d8713cea, < 47073aab8a3a5a7b41c9bd37d2a3dcbeeccd6c8a
Fixed in
  • 47073aab8a3a5a7b41c9bd37d2a3dcbeeccd6c8a

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

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