CVE-2020-1914: Facebook Hermes

Critical severity, CVSS 9.8. EPSS: 2.5% chance of exploitation in the next 30 days.

A logic vulnerability when handling the SaveGeneratorLong instruction in Facebook Hermes prior to commit b2021df620824627f5a8c96615edbd1eb7fdddfc allows attackers to potentially read out of bounds or theoretically 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 2020-10-01 (fixed in 2020-10-01)

Published 2020-10-08. Last modified 2026-06-17.