CVE-2023-6856

Name: CVE-2023-6856
Creator: NVD / NIST
Published: 2023-12-19T14:15:07.313+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 8.8/10EPSS 20.47%

Last modified Jun 17, 2026

CVE-2023-6856 is a high-severity vulnerability rated 8.8/10 on the CVSS scale. The WebGL `DrawElementsInstanced` method was susceptible to a heap buffer overflow when used on systems with the Mesa VM driver. This issue could allow an attacker to perform remote code execution and sandbox escape. EPSS estimates a 20.47% chance of exploitation in the next 30 days.

Description

The WebGL `DrawElementsInstanced` method was susceptible to a heap buffer overflow when used on systems with the Mesa VM driver. This issue could allow an attacker to perform remote code execution and sandbox escape. This vulnerability affects Firefox ESR < 115.6, Thunderbird < 115.6, and Firefox < 121.

Metrics

CVSS 3.1

8.8/10

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

EPSS Probability

20.47%

97.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-787

Affected Software

Vendor	Product	Versions
Mozilla	Firefox	< 121.0
Mozilla	Firefox Esr	< 115.6
Mozilla	Thunderbird	< 115.6
Debian	Debian Linux	10.0
Debian	Debian Linux	11.0
Debian	Debian Linux	12.0

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1843782Issue Tracking, Permissions Required
https://lists.debian.org/debian-lts-announce/2023/12/msg00020.htmlMailing List, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2023/12/msg00021.htmlMailing List, Third Party Advisory
https://security.gentoo.org/glsa/202401-10Third Party Advisory
https://www.debian.org/security/2023/dsa-5581Third Party Advisory
https://www.debian.org/security/2023/dsa-5582Third Party Advisory
https://www.mozilla.org/security/advisories/mfsa2023-54/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2023-55/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2023-56/Vendor Advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1843782Issue Tracking, Permissions Required
https://lists.debian.org/debian-lts-announce/2023/12/msg00020.htmlMailing List, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2023/12/msg00021.htmlMailing List, Third Party Advisory
https://security.gentoo.org/glsa/202401-10Third Party Advisory
https://www.debian.org/security/2023/dsa-5581Third Party Advisory
https://www.debian.org/security/2023/dsa-5582Third Party Advisory
https://www.mozilla.org/security/advisories/mfsa2023-54/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2023-55/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2023-56/Vendor Advisory

Timeline

Published: Dec 19, 2023
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2023-6856?

How severe is CVE-2023-6856?

CVE-2023-6856 has a CVSS score of 8.8/10 (HIGH severity). The EPSS model estimates a 20.47% probability of exploitation in the next 30 days.

How do I fix CVE-2023-6856?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2023-6856?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST