CVE-2023-4578: Mozilla Firefox

Medium severity, CVSS 6.5. EPSS: 0.6% chance of exploitation in the next 30 days.

When calling `JS::CheckRegExpSyntax` a Syntax Error could have been set which would end in calling `convertToRuntimeErrorAndClear`. A path in the function could attempt to allocate memory when none is available which would have caused a newly created Out of Memory exception to be mishandled as a Syntax Error. 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)

Published 2023-09-11. Last modified 2026-06-17.