# CVE-2021-46143: Integer overflow in n/a

> An integer overflow in libexpat's XML parser can cause a denial of service, affecting applications that process untrusted XML.

- **Severity:** High 8.1 (`CVSS:3.1/AC:H/AV:N/A:H/C:H/I:H/PR:N/S:U/UI:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 6 Jan 2022
- **Updated:** 14 Oct 2026
- **Also known as:** ALPINE-CVE-2021-46143, AZL-7155, CLEANSTART-2026-LJ99909, DEBIAN-CVE-2021-46143, GHSA-j6g2-cvhq-p8xr, JLSEC-2025-43, UBUNTU-CVE-2021-46143

## What is CVE-2021-46143?

CVE-2021-46143 is a high-severity vulnerability in Libexpat Project Libexpat, published on 6 Jan 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In doProlog in xmlparse.c in Expat (aka libexpat) before 2.4.3, an integer overflow exists for m_groupSize.

Weakness: CWE-190 (Integer Overflow or Wraparound)

## Which versions are affected by CVE-2021-46143?

It affects 8 products.


Products: Libexpat Project Libexpat, Netapp Active Iq Unified Manager, Netapp Clustered Data Ontap, Netapp Hci Baseboard Management Controller, Netapp Oncommand Workflow Automation, Netapp Solidfire \& Hci Management Node, Siemens Sinema Remote Connect Server, Tenable Nessus.

## How do I fix CVE-2021-46143?

Upgrade to a fixed version.

## Is CVE-2021-46143 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-46143 exists.

Public exploit code:

- https://github.com/nanopathi/external_expat_AOSP10_r33_CVE-2021-46143 (github_poc): https://github.com/nanopathi/external_expat_AOSP10_r33_CVE-2021-46143

## Other vulnerabilities in Libexpat Project Libexpat

- [CVE-2024-45490](https://insights.sbomify.com/CVE-2024-45490/): Integer overflow in n/a (critical 9.8)
- [CVE-2026-66046](https://insights.sbomify.com/CVE-2026-66046/): Expat Denial of Service via storeAtts() Quadratic Complexity (high 8.7)
- [CVE-2017-11742](https://insights.sbomify.com/CVE-2017-11742/): Privilege escalation in n/a (high 7.8)
- [CVE-2025-59375](https://insights.sbomify.com/CVE-2025-59375/): Denial of service in libexpat (high 7.5)
- [CVE-2023-52425](https://insights.sbomify.com/CVE-2023-52425/): Denial of service in n/a (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-46143 and fix it if it is affected.

What it is: CVE-2021-46143 is a high-severity vulnerability in Libexpat Project Libexpat, published on 6 Jan 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-46143 exists.

Affected product: Libexpat Project Libexpat. 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-2021-46143/ (Markdown: https://insights.sbomify.com/CVE-2021-46143/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-46143
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-46143
- OSV: https://osv.dev/vulnerability/CVE-2021-46143

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-46143/
Summaries are generated and may contain mistakes; the official description above is the record.