CVE-2023-23556 Memory corruption in Hermes

Critical 9.8 Published 18 May 2023 Updated 31 Jan 2025

A memory corruption vulnerability in the Hermes JavaScript engine allows arbitrary code execution when processing untrusted JavaScript.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2023-23556?

CVE-2023-23556 is a critical memory corruption vulnerability in Facebook Hermes, published on 18 May 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official 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.

Weakness: CWE-787

Which versions are affected by CVE-2023-23556?

It affects 1 product.

Products include Facebook Hermes.

How do I fix CVE-2023-23556?

No fix has been published for CVE-2023-23556 yet. Limit exposure of the affected software until one is available.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2023-23556 being exploited?

There is no known exploitation of CVE-2023-23556 in the wild and no public exploit code.

Sources

Also known as GHSA-5wwx-r37w-hqhw.