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MesaApplication · Mesa3d

CVE-2026-40393

CRITICAL · 9.8 CVSS v3.1 Published 2026-04-12
Fix available
A fix is available. Upgrade to 25.3.6 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

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 Mesa before 25.3.6 and 26 before 26.0.1, out-of-bounds memory access can occur in WebGPU because the amount of to-be-allocated data depends on an untrusted party, and is then used for alloca.

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 · moderate confidence

Mesa's WebGPU implementation contains an out-of-bounds memory access vulnerability where the allocation size is derived from untrusted input and then allocated on the stack using alloca. An attacker can manipulate the size parameter to cause stack-based buffer overflows or excessive stack consumption, leading to out-of-bounds memory access.

MitigationUpgrade Mesa to version 25.3.6 or 26.0.1 or later. Additionally, consider implementing input validation bounds on WebGPU allocation requests and replacing alloca with heap-based allocation (malloc) to prevent stack-based exploitation.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

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
MesaApplication
Affected:< 25.3.6= 26.0.0

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
High
Integrity
High
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed Mesa version
    Run 'glxinfo | grep Mesa' or check your system's package manager for the mesa package version
    Affected if The version is less than 25.3.6 or exactly 26.0.0
  2. Determine if WebGPU is in use
    Check for WebGPU-enabled applications or browser instances that may be using Mesa's WebGPU backend. Inspect any application logs or configuration that references WebGPU.
    Affected if WebGPU functionality is actively used or enabled in the environment
  3. Check for WebGPU-related Mesa environment or config
    Look for environment variables or configuration files that enable WebGPU in Mesa (e.g., relevant DRI configuration or environment settings).
    Affected if WebGPU support is explicitly enabled in Mesa configuration
  4. Verify WebGPU support status in the system
    Query the system's graphics driver status or Mesa driver info to see if WebGPU support is compiled in or active.
    Affected if WebGPU support is present and active in the installed Mesa build

A system is affected if it runs a Mesa version below 25.3.6 or exactly 26.0.0 AND has WebGPU functionality enabled or in use.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 25.3.6 or later
Fixed in 25.3.6
Interim mitigation

Upgrade Mesa to version 25.3.6 or 26.0.1 or later. Additionally, consider implementing input validation bounds on WebGPU allocation requests and replacing alloca with heap-based allocation (malloc) to prevent stack-based exploitation.

Recommended fix High confidence

Mesa 25.3.6+ or Mesa 26.0.1+ (depending on which branch you are on)

  1. 1. Identify the currently installed Mesa version using 'glxinfo | grep 'OpenGL version' or 'mesa-utils --version'
  2. 2. If running Mesa 25.x (<25.3.6), upgrade to version 25.3.6 or later via system package manager (e.g., 'apt update && apt upgrade', 'dnf update', 'pacman -Syu')
  3. 3. If running Mesa 26.0.0, upgrade to version 26.0.1 or later
  4. 4. Verify the upgrade was successful by checking the installed version matches or exceeds the fixed release
  5. 5. Restart any graphics-intensive applications or the system to ensure the new Mesa libraries are loaded
Caveat Major version upgrades of Mesa may include driver changes that could affect GPU compatibility or performance; review release notes for the target version

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

Fix this in Mesa Scoped from the published advisory
  • Consultation6.0 h
  • Implementation12.0 h
  • Testing10.0 h
  • Review / QA6.0 h
34.0 hours of engineering $5,940
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $9,504.

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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-2026-40393 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
  • No spam, self-promotion, credentials, or personal data