CyberSecBulletin
CVE-2026-63844NVD status: Analyzed

Linux: Improper Check for Unusual or Exceptional Conditions

Published Updated By the CyberSecBulletin desk

CVE-2026-63844 is a high-severity improper check for unusual or exceptional conditions vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions b884ff67d62ef514eee9d5f605c03101c8b6bc98, d6bd2a5fd611ec9c8a2411f084cff2435c709608, 8549b3933038e68dc61cb934b9a54223dd244a78 as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.18% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to b884ff67d62ef514eee9d5f605c03101c8b6bc98 or d6bd2a5fd611ec9c8a2411f084cff2435c709608 or 8549b3933038e68dc61cb934b9a54223dd244a78 or 249fa7549736de1c8e327d7ca6b32fa148a40bd6, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 6.6.141 or 6.12.91 or 6.18.33 or 7.0.10, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxe684e654eba9481a9f462a7bbf5c385b7d1c076e up to, but not including, b884ff67d62ef514eee9d5f605c03101c8b6bc98; e684e654eba9481a9f462a7bbf5c385b7d1c076e up to, but not including, d6bd2a5fd611ec9c8a2411f084cff2435c709608; e684e654eba9481a9f462a7bbf5c385b7d1c076e up to, but not including, 8549b3933038e68dc61cb934b9a54223dd244a78; e684e654eba9481a9f462a7bbf5c385b7d1c076e up to, but not including, 249fa7549736de1c8e327d7ca6b32fa148a40bd6; e684e654eba9481a9f462a7bbf5c385b7d1c076e up to, but not including, 83e37c0987ca92f9e87789b46dd311dcf5a4a6c8; 6.5b884ff67d62ef514eee9d5f605c03101c8b6bc98, d6bd2a5fd611ec9c8a2411f084cff2435c709608, 8549b3933038e68dc61cb934b9a54223dd244a78, 249fa7549736de1c8e327d7ca6b32fa148a40bd6, 83e37c0987ca92f9e87789b46dd311dcf5a4a6c8
LinuxLinux Kernel6.5 up to, but not including, 6.6.141; 6.7 up to, but not including, 6.12.91; 6.13 up to, but not including, 6.18.33; 6.19 up to, but not including, 7.0.10; 7.16.6.141, 6.12.91, 6.18.33, 7.0.10

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by CNA.

Official description

In the Linux kernel, the following vulnerability has been resolved: drm/amdgpu/jpeg: set no_user_fence for JPEG v4.0.3 ring JPEG rings do not support 64-bit user fence writes, reject CS submissions with user fences. (cherry picked from commit 2f6afc97d259d530f4f86c7743efbc573a8da927)

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Check for Unusual or Exceptional Conditions

The product does not check or incorrectly checks for unusual or exceptional conditions that are not expected to occur frequently during day to day operation of the product.

How developers prevent this class of flaw

  • Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Choose languages with features such as exception handling that force the programmer to anticipate unusual conditions that may generate exceptions. Custom exceptions may need to be developed to handle unusual business-logic conditions. Be careful not to pass sensitive exceptions back to the user (CWE-209, CWE-248).
  • Check the results of all functions that return a value and verify that the value is expected.
  • If using exception handling, catch and throw specific exceptions instead of overly-general exceptions (CWE-396, CWE-397). Catch and handle exceptions as locally as possible so that exceptions do not propagate too far up the call stack (CWE-705). Avoid unchecked or uncaught exceptions where feasible (CWE-248).

More Improper Check for Unusual or Exceptional Conditions vulnerabilities (CWE-754)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Improper Check for Unusual or Exceptional Conditions vulnerabilities

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