# CVE-2026-97151: Code injection in mammoth.js

> Attackers can achieve code execution via prototype pollution in mammoth.js, and potentially read local files if external access is enabled.

- **Severity:** High 8.4 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:L/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 24 Sep 2026
- **Updated:** 24 Sep 2026
- **Also known as:** GHSA-89qm-22qm-xf5h

## What is CVE-2026-97151?

CVE-2026-97151 is a high-severity code injection vulnerability in mwilliamson mammoth.js, published on 24 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

mammoth (aka mammoth.js) before 1.12.2 is vulnerable to prototype pollution when reading the styles defined in a document. Converting a crafted .docx file allows an attacker to add arbitrary properties to Object.prototype. In 1.11.0 through 1.12.1, applications that convert further documents in the same process and return the converted HTML can also disclose the contents of local server files (to the party supplying the documents) by setting externalFileAccess to true.

Weakness: CWE-1321 (Improperly Controlled Modification of Object Prototype Attributes)

## Which versions are affected by CVE-2026-97151?


## How do I fix CVE-2026-97151?

No fix has been published for CVE-2026-97151 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-97151 being exploited?

There is no known exploitation of CVE-2026-97151 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-97151 and fix it if it is affected.

What it is: CVE-2026-97151 is a high-severity code injection vulnerability in mwilliamson mammoth.js, published on 24 Sep 2026. 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-2026-97151 in the wild and no public exploit code.

Affected product: mwilliamson mammoth.js. 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-2026-97151/ (Markdown: https://insights.sbomify.com/CVE-2026-97151/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-97151
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-97151
- OSV: https://osv.dev/vulnerability/CVE-2026-97151

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-97151/
Summaries are generated and may contain mistakes; the official description above is the record.