What is CVE-2023-25933?

CVE-2023-25933 is a critical-severity vulnerability in Facebook Hermes, classified under Access of Resource Using Incompatible Type (Type Confusion). CVSS score: 9.8/10. Published 2023-05-18.

How severe is CVE-2023-25933?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Vulnerability in Facebook Hermes

CVE-2023-25933

A type confusion bug in TypedArray prior to commit e6ed9c1a4b02dc219de1648f44cd808a56171b81 could have been used by a malicious attacker to execute arbitrary code via untrusted JavaScript. Note that this is only exploitable in cases where Hermes is used to execute untrusted JavaScript. Hence, most React Native applications are not affected.

Published 2023-05-18 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.009 (59.0th percentile), scored 2026-10-24.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 59th percentile — 59.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.009 · newest: 0.009 · change: 0.000

Affected products

Facebook Hermes — versions 0

Weakness classification (CWE)

CWE-843 — Access of Resource Using Incompatible Type (Type Confusion)

References

www.facebook.com/security/advisories/cve-2023-25933 (Patch, Vendor Advisory)
github.com/facebook/hermes/commit/e6ed9c1a4b02dc219de1648f44cd808a56171b81 (Patch)

Frequently asked questions

What is CVE-2023-25933?: CVE-2023-25933 is a critical-severity vulnerability in Facebook Hermes, classified under Access of Resource Using Incompatible Type (Type Confusion). CVSS score: 9.8/10. Published 2023-05-18.
How severe is CVE-2023-25933?: Critical severity. CVSS v3 base score is 9.8 out of 10.