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Linux KernelOperating system · Linux

CVE-2026-31638

HIGH · 7.5 CVSS v3.1 Published 2026-04-24
Fix available
A fix is available. Upgrade to 6.6.135 / 6.12.82 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In the Linux kernel, the following vulnerability has been resolved: rxrpc: Only put the call ref if one was acquired rxrpc_input_packet_on_conn() can process a to-client packet after the current client call on the channel has already been torn down. In that case chan->call is NULL, rxrpc_try_get_call() returns NULL and there is no reference to drop. The client-side implicit-end error path does not account for that and unconditionally calls rxrpc_put_call(). This turns a protocol error path into a kernel crash instead of rejecting the packet. Only drop the call reference if one was actually acquired. Keep the existing protocol error handling unchanged.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis
How this class of weakness works · CWE-476

The code follows a pointer that is null, crashing the process. An attacker who can reliably trigger it turns the crash into a denial of service. The fix is checking for null before use and handling the failure path gracefully.

General guidance for the null pointer dereference class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 6.2.1, < 6.6.135>= 6.7, < 6.12.82>= 6.13, < 6.18.23>= 6.19, < 6.19.13= 6.2= 7.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 6.6.135 / 6.12.82 / 6.18.23 or later
Fixed in 6.6.1356.12.826.18.23
Vendor patch git.kernel.org →
Recommended fix High confidence

For branch 6.2.x-6.6.x: upgrade to 6.6.135 or later. For branch 6.7.x-6.12.x: upgrade to 6.12.82 or later. For branch 6.13.x-6.18.x: upgrade to 6.18.23 or later. For branch 6.19.x: upgrade to 6.19.13 or later.

  1. Identify the currently running Linux kernel version using 'uname -r'
  2. Determine which version range your current kernel falls into based on the affected ranges: 6.2.1-6.6.134, 6.7-6.12.81, 6.13-6.18.22, or 6.19-6.19.12
  3. Upgrade to the appropriate fixed kernel version for your branch: for 6.2.x-6.6.x upgrade to >= 6.6.135; for 6.7.x-6.12.x upgrade to >= 6.12.82; for 6.13.x-6.18.x upgrade to >= 6.18.23; for 6.19.x upgrade to >= 6.19.13
  4. Apply the upgrade via your distribution's package manager (e.g., 'apt update && apt upgrade linux-image' for Debian/Ubuntu, 'yum update kernel' for RHEL/CentOS, or 'pacman -Syu linux' for Arch)
  5. Reboot the system to load the fixed kernel
  6. Verify the new kernel version is running with 'uname -r'
Caveat Kernel upgrades may require system reboot and could introduce compatibility changes with third-party kernel modules; ensure driver compatibility before upgrading

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $3,200. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-31638 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
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