# CVE-2020-1896: Memory corruption in Hermes

> A stack overflow in the Hermes JavaScript engine allows arbitrary code execution if the application evaluates 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:** 2 Feb 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-28c6-6wvh-6235

## What is CVE-2020-1896?

CVE-2020-1896 is a critical memory corruption vulnerability in Facebook Hermes, published on 2 Feb 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A stack overflow vulnerability in Facebook Hermes 'builtin apply' prior to commit 86543ac47e59c522976b5632b8bf9a2a4583c7d2 (https://github.com/facebook/hermes/commit/86543ac47e59c522976b5632b8bf9a2a4583c7d2) allows attackers to potentially execute arbitrary code via crafted JavaScript. Note that this is only exploitable if the application using Hermes permits evaluation of untrusted JavaScript. Hence, most React Native applications are not affected.

Weakness: CWE-787 (Out-of-bounds Write), CWE-121 (Stack-based Buffer Overflow)

## Which versions are affected by CVE-2020-1896?

It affects 1 product.


Products: Facebook Hermes.

## How do I fix CVE-2020-1896?

No fix has been published for CVE-2020-1896 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-1896 being exploited?

There is no known exploitation of CVE-2020-1896 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-2023-23557](https://insights.sbomify.com/CVE-2023-23557/): 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)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-1896 and fix it if it is affected.

What it is: CVE-2020-1896 is a critical memory corruption vulnerability in Facebook Hermes, published on 2 Feb 2021. 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-2020-1896 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-2020-1896/ (Markdown: https://insights.sbomify.com/CVE-2020-1896/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-1896
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-1896
- OSV: https://osv.dev/vulnerability/CVE-2020-1896

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-1896/
Summaries are generated and may contain mistakes; the official description above is the record.