What’s Vulnerable › Vulnerabilities

CVE-2020-1911

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 2.0% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-09-04 · updated 2026-06-17
• Weakness: CWE-843

Description

A type confusion vulnerability when resolving properties of JavaScript objects with specially-crafted prototype chains in Facebook Hermes prior to commit fe52854cdf6725c2eaa9e125995da76e6ceb27da 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 0.4.3 — fixed in 0.4.3

How to fix

Upgrade to a fixed version: Facebook Hermes 0.4.3. Check the vendor advisory for mitigations.

References

• https://github.com/facebook/hermes/commit/fe52854cdf6725c2eaa9e125995da76e6ceb27da
• https://www.facebook.com/security/advisories/cve-2020-1911
• https://github.com/facebook/hermes/commit/fe52854cdf6725c2eaa9e125995da76e6ceb27da
• https://www.facebook.com/security/advisories/cve-2020-1911

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