PatchTheCVECVE-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
CVE-2026-40393 is a high-severity flaw (CVSS 8.1) affecting mesa. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
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.
Why this priority
- High severity
- Remotely exploitable, no login, no user action
A fixed release or distro patch exists.
Risk facts
| CVSS score | 8.1 (High) |
| Attack vector | Network (remote) |
| Attack complexity | High |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | 0.4% (top 63%) |
| CISA exploited list | No |
| Weakness | CWE-787 |
| Published | 2026-04-12 |
| Last modified | 2026-10-26 |
Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2026-40393?
mesa: upgrade to 25.3.6. Exact commands for each OS are on this page.
Is CVE-2026-40393 being exploited?
CVE-2026-40393 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2026-40393 affect?
CVE-2026-40393 affects mesa. Severity is high (CVSS 8.1). 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.
How urgent is CVE-2026-40393?
Priority 43/100. High severity; Remotely exploitable, no login, no user action