What’s Vulnerable › Vulnerabilities

CVE-2023-6864

• Severity: high (CVSS 8.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2023-12-19 · updated 2026-06-17
• Weakness: CWE-787

Description

Memory safety bugs present in Firefox 120, Firefox ESR 115.5, and Thunderbird 115.5. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox ESR < 115.6, Thunderbird < 115.6, and Firefox < 121.

Affected products

• Debian Linux: 10.0, 11.0, 12.0
• Mozilla Firefox: before 121.0 — fixed in 121.0
• Mozilla Firefox ESR: before 115.6 — fixed in 115.6
• Mozilla Thunderbird: before 115.6 — fixed in 115.6

How to fix

Upgrade to a fixed version: Mozilla Firefox 121.0; Mozilla Firefox ESR 115.6; Mozilla Thunderbird 115.6. Check the vendor advisory for mitigations.

References

• https://bugzilla.mozilla.org/buglist.cgi?bug_id=1736385%2C1810805%2C1846328%2C1856090%2C1858033%2C1858509%2C1862089%2C1862777%2C1864015
• https://lists.debian.org/debian-lts-announce/2023/12/msg00020.html
• https://lists.debian.org/debian-lts-announce/2023/12/msg00021.html
• https://security.gentoo.org/glsa/202401-10
• https://www.debian.org/security/2023/dsa-5581
• https://www.debian.org/security/2023/dsa-5582
• https://www.mozilla.org/security/advisories/mfsa2023-54/
• https://www.mozilla.org/security/advisories/mfsa2023-55/
• https://www.mozilla.org/security/advisories/mfsa2023-56/
• https://bugzilla.mozilla.org/buglist.cgi?bug_id=1736385%2C1810805%2C1846328%2C1856090%2C1858033%2C1858509%2C1862089%2C1862777%2C1864015
• https://lists.debian.org/debian-lts-announce/2023/12/msg00020.html
• https://lists.debian.org/debian-lts-announce/2023/12/msg00021.html

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