What’s Vulnerable › Vulnerabilities

CVE-2023-5171

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2023-09-27 · updated 2026-06-17
• Weakness: CWE-416

Description

During Ion compilation, a Garbage Collection could have resulted in a use-after-free condition, allowing an attacker to write two NUL bytes, and cause a potentially exploitable crash. This vulnerability affects Firefox < 118, Firefox ESR < 115.3, and Thunderbird < 115.3.

Affected products

• Debian Linux: 10.0, 11.0, 12.0
• Fedoraproject Fedora: 39
• Mozilla Firefox: before 118 — fixed in 118
• Mozilla Firefox ESR: before 115.3 — fixed in 115.3
• Mozilla Thunderbird: before 115.3 — fixed in 115.3

How to fix

Upgrade to a fixed version: Mozilla Firefox 118; Mozilla Firefox ESR 115.3; Mozilla Thunderbird 115.3. Check the vendor advisory for mitigations.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1851599
• https://lists.debian.org/debian-lts-announce/2023/09/msg00034.html
• https://lists.debian.org/debian-lts-announce/2023/10/msg00015.html
• https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/AY642Z6JZODQJE7Z62CFREVUHEGCXGPD/
• https://www.debian.org/security/2023/dsa-5506
• https://www.debian.org/security/2023/dsa-5513
• https://www.mozilla.org/security/advisories/mfsa2023-41/
• https://www.mozilla.org/security/advisories/mfsa2023-42/
• https://www.mozilla.org/security/advisories/mfsa2023-43/
• https://bugzilla.mozilla.org/show_bug.cgi?id=1851599
• https://lists.debian.org/debian-lts-announce/2023/09/msg00034.html
• https://lists.debian.org/debian-lts-announce/2023/10/msg00015.html

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