Critical (9.8) in facebook hermes. EPSS 2.5% chance of exploitation in the next 30 days. Fixed in hermes-engine 0.7.2.
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.
Severity
CVSS 3.1
9.8 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS
2.5% chance of exploitation in the next 30 days; higher than 84% of CVEs (scores of 2026-10-31)