CVE-2026-31637: In the Linux kernel, the following vulnerability has been resolved: rxrpc: reject undecryptable rxkad respons

Q: How do I fix CVE-2026-31637?

linux kernel: upgrade to 6.6.135, 6.12.82, 6.18.23, 6.19.13. Exact commands for each OS are on this page.

Q: Is CVE-2026-31637 being exploited?

CVE-2026-31637 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-31637 affect?

CVE-2026-31637 affects linux kernel. Severity is critical (CVSS 9.8). 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 whet

Q: How urgent is CVE-2026-31637?

Priority 59/100. Critical severity; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action; On your watchlist

This month

CRITICAL 9.8REMOTEWATCHLISTUPGRADE

CVE-2026-31637 is a critical-severity flaw (CVSS 9.8) affecting linux kernel. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 by

Why this priority

Critical severity
CISA SSVC: automatable with total technical impact
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.6% (top 52%)
CISA exploited list	No
Weakness	CWE-754
Published	2026-04-24
Last modified	2026-10-19

Publisher (CNA): kernel.org · Vendor: linux

Last updated 2026-10-19 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-24 15:16 UTCPublished CVE record published
2026-10-19 19:18 UTCUpdated Record last modified

linux linux kernel UPGRADE

Affected: >= 2.6.22.1 and < 6.6.135 · >= 6.7 and < 6.12.82 · >= 6.13 and < 6.18.23 · >= 6.19 and < 6.19.13 · 2.6.22 · 7.0 rc1 · 7.0 rc2 · 7.0 rc3

Fixed in: 6.6.135, 6.12.82, 6.18.23, 6.19.13

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Exact fixes by distribution

Fedora 46 · python-python-ulid · FIXED · 4.1.0-2.fc46 · FEDORA-2026-3652e4825b · source

sudo dnf upgrade --advisory=FEDORA-2026-3652e4825b

Fedora ELN · gmp · FIXED · 6.3.0-7.eln159 · FEDORA-2026-1139089b36 · source

sudo dnf upgrade --advisory=FEDORA-2026-1139089b36

Debian 12 · linux · FIXED · 6.1.176-1

sudo apt update && sudo apt install --only-upgrade linux dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "6.1.176-1" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · linux · FIXED · 6.12.85-1

sudo apt update && sudo apt install --only-upgrade linux dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "6.12.85-1" && echo PATCHED || echo STILL-VULNERABLE

RHEL 10 · kernel · DEFERRED

RHEL 6 · kernel · NOT AFFECTED

RHEL 7 · kernel · DEFERRED

RHEL 7 · kernel-rt · DEFERRED

RHEL 8 · kernel · DEFERRED

Amazon Linux 2023 · see advisory · FIXED · ALAS2023-2026-1695 · source

sudo dnf update --advisory=ALAS2023-2026-1695

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Write-up: cert-portal.siemens.com/productcert/html/ssa-784472.html

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-31637?

linux kernel: upgrade to 6.6.135, 6.12.82, 6.18.23, 6.19.13. Exact commands for each OS are on this page.

Is CVE-2026-31637 being exploited?

CVE-2026-31637 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-31637 affect?

CVE-2026-31637 affects linux kernel. Severity is critical (CVSS 9.8). 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 whet

How urgent is CVE-2026-31637?

Priority 59/100. Critical severity; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Linux kernel vulnerabilities

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References

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