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TI-2020-01838 Aliases CVE-2020-1911GHSA-f5x2-xv93-4p23

Type confusion in Meta Hermes

Priority MEDIUM 46CWE-843Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Code execution
Confidentiality · integrity · availability
High · High · High
Fix status
Fixed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA and GitHub. Impact type from CWE-843 and the CVSS impact.

Summary

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.

Why it matters now

EPSS 0.02003 80th percentileScored 2026-11-07
Fix Fixed hermes-engine (npm): 0.5.2

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
MetaHermescommit prior to fe52854cdf6725c2eaa9e125995da76e6ceb27da—No fix listedCNA
—hermes-engine (npm)before 0.5.20.5.2Patch availableGHSA-f5x2-xv93-4p23
  • Hermes VendorMeta Affected commit prior to fe52854cdf6725c2eaa9e125995da76e6ceb27da Fixed in — No fix listed CNA
  • hermes-engine (npm) Vendor— Affected before 0.5.2 Fixed in 0.5.2 Patch available GHSA-f5x2-xv93-4p23

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:facebook:hermes:*:*:*:*:*:*:*:*before 0.4.3VulnerableMeta
  • cpe:2.3:a:facebook:hermes:*:*:*:*:*:*:*:* Versions before 0.4.3 Vulnerable ·Meta

Remediation

  • Fix · GHSA-f5x2-xv93-4p23 hermes-engine (npm) Fixed in 0.5.2 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2020-1911
  2. 2026-10-03 Alias added: GHSA-f5x2-xv93-4p23

References

Patch 1

Advisory 2

  • TI-2023-14306 Use after free in Meta Hermes CVSS 3.1CRITICAL 9.8
  • TI-2023-12661 Use after free in Meta Hermes CVSS 3.1CRITICAL 9.8
  • TI-2023-11181 Type confusion in Meta Hermes CVSS 3.1CRITICAL 9.8
  • TI-2023-09388 Type confusion in Meta Hermes CVSS 3.1CRITICAL 9.8
  • TI-2023-09387 Out-of-bounds write in Meta Hermes CVSS 3.1CRITICAL 9.8
  • TI-2020-01841 A logic vulnerability when handling the SaveGeneratorLong instruction in Facebook Hermes… CVSS 3.1CRITICAL 9.8
See all 19 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences