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 depends on an untrusted party, and is then used for alloca.

Published: 2026-04-12 Last update: 2026-04-16 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-40393 is rated Low Risk (38.1/100): CVSS High severity, with low exploitation likelihood (EPSS 0.05%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-40393

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-04-18 0.04% 0.05% +0.01%
2 2026-04-13 — 0.04% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-40393

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.1 3.1 HIGH
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.2 5.9 [email protected]
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]

Weakness enumeration for CVE-2026-40393

OS Trackers for CVE-2026-40393

vendor priority summary link
alpine — CVE-2026-40393: 1 source package rows (mesa); 48 state rows across 6 repos (3.19-main, 3.20-main, 3.21-main, 3.22-main, 3.23-main, edge-main); fixed 0, open 48. https://security.alpinelinux.org/vuln/CVE-2026-40393
debian not yet assigned CVE-2026-40393 not yet assigned priority: Debian including 1 source packages (mesa), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): open 3, resolved 2. https://security-tracker.debian.org/tracker/CVE-2026-40393
suse medium CVE-2026-40393 severity moderate: SUSE including 136 source package names (Mesa-17.0.5-117.14.1, Mesa-18.3.2-14.12.1, …), 139 product×package rows across 10 product lines (SUSE Linux Enterprise Micro 5.2, SUSE Linux Enterprise Micro 5.3, … (10 product lines)): First Fixed 138, Fixed 1. https://www.suse.com/security/cve/CVE-2026-40393/
ubuntu medium CVE-2026-40393 medium priority: Ubuntu including 1 source packages (mesa), 8 status rows across 8 suites (bionic, focal, jammy, noble, questing, trusty, upstream, xenial): needs-triage 7, released 1. https://ubuntu.com/security/CVE-2026-40393

Affected software / configurations for CVE-2026-40393

Vendor Product Version Raw CPE
mesa3d mesa < 25.3.6 cpe:2.3:a:mesa3d:mesa:*:*:*:*:*:*:*:*
mesa3d mesa 26.0.0 cpe:2.3:a:mesa3d:mesa:26.0.0:*:*:*:*:*:*:*

References for CVE-2026-40393

cvelogic Threat Intelligence