What’s Vulnerable › Vulnerabilities

CVE-2023-4577: Memory corruption in JIT UpdateRegExpStatics

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2023-09-11 · updated 2026-06-17

Description

When `UpdateRegExpStatics` attempted to access `initialStringHeap` it could already have been garbage collected prior to entering the function, which could potentially have led to an exploitable crash. This vulnerability affects Firefox < 117, Firefox ESR < 115.2, and Thunderbird < 115.2.

Affected products

• Mozilla Firefox: before 117.0 — fixed in 117.0
• Mozilla Firefox ESR: before 115.2 — fixed in 115.2
• Mozilla Thunderbird: before 115.2 — fixed in 115.2

How to fix

Upgrade to a fixed version: Mozilla Firefox 117.0; Mozilla Firefox ESR 115.2; Mozilla Thunderbird 115.2. Check the vendor advisory for mitigations.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1847397
• https://www.mozilla.org/security/advisories/mfsa2023-34/
• https://www.mozilla.org/security/advisories/mfsa2023-36/
• https://www.mozilla.org/security/advisories/mfsa2023-38/
• https://bugzilla.mozilla.org/show_bug.cgi?id=1847397
• https://www.mozilla.org/security/advisories/mfsa2023-34/
• https://www.mozilla.org/security/advisories/mfsa2023-36/
• https://www.mozilla.org/security/advisories/mfsa2023-38/

Get alerted when CVE-2023-4577 or the next vulnerability affects your stack