# CVE-2023-23557: Memory corruption in Hermes

> A type confusion vulnerability in the Hermes JavaScript engine allows arbitrary code execution when processing untrusted JavaScript.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 18 May 2023
- **Updated:** 21 Jan 2025
- **Also known as:** GHSA-j9jr-2qmg-cr6m

## What is CVE-2023-23557?

CVE-2023-23557 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 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.

Weakness: CWE-843 (Access of Resource Using Incompatible Type)

## Which versions are affected by CVE-2023-23557?

It affects 1 product.


Products: Facebook Hermes.

## How do I fix CVE-2023-23557?

No fix has been published for CVE-2023-23557 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-23557 being exploited?

There is no known exploitation of CVE-2023-23557 in the wild and no public exploit code.

## Other vulnerabilities in Facebook Hermes

- [CVE-2023-23556](https://insights.sbomify.com/CVE-2023-23556/): Memory corruption in Hermes (critical 9.8)
- [CVE-2023-25933](https://insights.sbomify.com/CVE-2023-25933/): Memory corruption in Hermes (critical 9.8)
- [CVE-2023-28081](https://insights.sbomify.com/CVE-2023-28081/): Use after free in Hermes (critical 9.8)
- [CVE-2023-30470](https://insights.sbomify.com/CVE-2023-30470/): Use after free in Hermes (critical 9.8)
- [CVE-2022-32234](https://insights.sbomify.com/CVE-2022-32234/): Memory corruption in Hermes (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-23557 and fix it if it is affected.

What it is: CVE-2023-23557 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.
Exploitation: There is no known exploitation of CVE-2023-23557 in the wild and no public exploit code.

Affected product: Facebook Hermes. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2023-23557/ (Markdown: https://insights.sbomify.com/CVE-2023-23557/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-23557
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-23557
- OSV: https://osv.dev/vulnerability/CVE-2023-23557

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-23557/
Summaries are generated and may contain mistakes; the official description above is the record.