CVE-2021-24037: Facebook Hermes

Critical severity, CVSS 9.8. EPSS: 1.8% chance of exploitation in the next 30 days.

A use after free in hermes, while emitting certain error messages, prior to commit d86e185e485b6330216dee8e854455c694e3a36e allows attackers to potentially execute arbitrary code via crafted JavaScript. Note that this is only exploitable if the application using Hermes permits evaluation of untrusted JavaScript. Hence, most React Native applications are not affected.

Affected products

• Facebook Hermes: before 0.8.0 (fixed in 0.8.0)

Published 2021-06-15. Last modified 2026-06-17.