What’s Vulnerable › Vulnerabilities

CVE-2023-23556

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.9% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2023-05-18 · updated 2026-06-17
• Weakness: CWE-787

Description

An error in BigInt conversion to Number in Hermes prior to commit a6dcafe6ded8e61658b40f5699878cd19a481f80 could have been used by a malicious attacker to execute arbitrary code due to an out-of-bound write. Note that this bug is only exploitable in cases where Hermes is used to execute untrusted JavaScript. Hence, most React Native applications are not affected.

Affected products

• Facebook Hermes: before 2023-02-02 — fixed in 2023-02-02

How to fix

Upgrade to a fixed version: Facebook Hermes 2023-02-02. Check the vendor advisory for mitigations.

References

• https://github.com/facebook/hermes/commit/a6dcafe6ded8e61658b40f5699878cd19a481f80
• https://www.facebook.com/security/advisories/cve-2023-23556
• https://github.com/facebook/hermes/commit/a6dcafe6ded8e61658b40f5699878cd19a481f80
• https://www.facebook.com/security/advisories/cve-2023-23556

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