CyberSecBulletin
CVE-2026-63855NVD status: Modified

In the Linux kernel, the following vulnerability has been resolved: drm/amdgpu/vcn: set…

Published Updated By the CyberSecBulletin desk

CVE-2026-63855 is a high-severity improper input validation 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 8156e258025f2a22fcf7486c96848ac3cd3541dd, 2c6fb056567efb49f8674108b86088a1cfaa86d0, 8f0ea4524dc71c6c9ec97f2711f46e12f624140f 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 8156e258025f2a22fcf7486c96848ac3cd3541dd or 2c6fb056567efb49f8674108b86088a1cfaa86d0 or 8f0ea4524dc71c6c9ec97f2711f46e12f624140f or 602d4c5872b25ddd4d82fb2025efb9a05b187bb3, 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
LinuxLinux28c17d72072b7ce5cc13a527dcbfc045cc995e7d up to, but not including, 8156e258025f2a22fcf7486c96848ac3cd3541dd; 28c17d72072b7ce5cc13a527dcbfc045cc995e7d up to, but not including, 2c6fb056567efb49f8674108b86088a1cfaa86d0; 28c17d72072b7ce5cc13a527dcbfc045cc995e7d up to, but not including, 8f0ea4524dc71c6c9ec97f2711f46e12f624140f; 28c17d72072b7ce5cc13a527dcbfc045cc995e7d up to, but not including, 602d4c5872b25ddd4d82fb2025efb9a05b187bb3; 28c17d72072b7ce5cc13a527dcbfc045cc995e7d up to, but not including, 5a3c6f76cab164a5d803084908d7050f649ab7f9; 28c17d72072b7ce5cc13a527dcbfc045cc995e7d up to, but not including, 4f317863a3ab212a027d8c8c3cc3af4e3fb95704; 5.48156e258025f2a22fcf7486c96848ac3cd3541dd, 2c6fb056567efb49f8674108b86088a1cfaa86d0, 8f0ea4524dc71c6c9ec97f2711f46e12f624140f, 602d4c5872b25ddd4d82fb2025efb9a05b187bb3, 5a3c6f76cab164a5d803084908d7050f649ab7f9, 4f317863a3ab212a027d8c8c3cc3af4e3fb95704
LinuxLinux Kernel5.4 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/vcn: set no_user_fence for VCN v2.5 enc/dec rings VCN encoder and decoder rings do not support 64-bit user fence writes, reject CS submissions with user fences. (cherry picked from commit efc9dd5590894109bce9a0bfe1fa5592dd6b20b1)

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

The underlying weakness: Improper Input Validation

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

How developers prevent this class of flaw

  • Consider using language-theoretic security (LangSec) techniques that characterize inputs using a formal language and build recognizers for that language. This effectively requires parsing to be a distinct layer that effectively enforces a boundary between raw input and internal data representations, instead of allowing parser code to be scattered throughout the program, where it could be subject to errors or inconsistencies that create weaknesses.
  • Use an input validation framework such as Struts or the OWASP ESAPI Validation API. Note that using a framework does not automatically address all input validation problems; be mindful of weaknesses that could arise from misusing the framework itself (CWE-1173).
  • Understand all the potential areas where untrusted inputs can enter the product, including but not limited to: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide data to the application. Remember that such inputs may be obtained indirectly through API calls.

More Improper Input Validation vulnerabilities (CWE-20)

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 Input Validation vulnerabilities

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