CVE-2023-23557
An error in Hermes' algorithm for copying objects properties prior to commit a00d237346894c6067a594983be6634f4168c9ad could be used by a malicious attacker to execute arbitrary code via type confusion.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.89%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
An error in Hermes' algorithm for copying objects properties prior to commit a00d237346894c6067a594983be6634f4168c9ad could be used by a malicious attacker to execute arbitrary code via type confusion. Note that this is only exploitable in cases where Hermes is used to execute untrusted JavaScript. Hence, most React Native applications are not affected.
- CVSS 3.1
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 0.89% probability · 59th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-843
- Affected
- facebook/hermes
- Source
- cve-assign@fb.com
EPSS 0.9% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://github.com/facebook/hermes/commit/a00d237346894c6067a594983be6634f4168c9adPatch, Vendor Advisory
- https://www.facebook.com/security/advisories/cve-2023-23557Patch, Vendor Advisory
- https://github.com/facebook/hermes/commit/a00d237346894c6067a594983be6634f4168c9adPatch, Vendor Advisory
- https://www.facebook.com/security/advisories/cve-2023-23557Patch, Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.