# CVE-2003-1564: Denial of service in n/a

> Attackers can cause denial of service via memory and CPU exhaustion using crafted XML with nested entity references in libxml2.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 2 Sep 2008
- **Updated:** 8 Aug 2024
- **Also known as:** GHSA-6wfm-7hqx-39wg

## What is CVE-2003-1564?

CVE-2003-1564 is a medium-severity denial of service vulnerability in Xmlsoft Libxml2, published on 2 Sep 2008. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

libxml2, possibly before 2.5.0, does not properly detect recursion during entity expansion, which allows context-dependent attackers to cause a denial of service (memory and CPU consumption) via a crafted XML document containing a large number of nested entity references, aka the "billion laughs attack."

Weakness: CWE-776 (Improper Restriction of Recursive Entity References in DTDs)

## Which versions are affected by CVE-2003-1564?

It affects 1 product.


Products: Xmlsoft Libxml2.

## How do I fix CVE-2003-1564?

Upgrade to a fixed version.

## Is CVE-2003-1564 being exploited?

There is no known exploitation of CVE-2003-1564 in the wild and no public exploit code.

## Other vulnerabilities in Xmlsoft Libxml2

- [CVE-2017-16931](https://insights.sbomify.com/CVE-2017-16931/): XML external entity in n/a (critical 9.8)
- [CVE-2017-8872](https://insights.sbomify.com/CVE-2017-8872/): Information disclosure in n/a (critical 9.1)
- [CVE-2022-49043](https://insights.sbomify.com/CVE-2022-49043/): Use after free in libxml2 (high 8.1)
- [CVE-2026-86140](https://insights.sbomify.com/CVE-2026-86140/): Memory corruption in libxml2 (high 8.0)
- [CVE-2024-34459](https://insights.sbomify.com/CVE-2024-34459/): Memory corruption in n/a (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2003-1564 and fix it if it is affected.

What it is: CVE-2003-1564 is a medium-severity denial of service vulnerability in Xmlsoft Libxml2, published on 2 Sep 2008. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2003-1564 in the wild and no public exploit code.

Affected product: Xmlsoft Libxml2. 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-2003-1564/ (Markdown: https://insights.sbomify.com/CVE-2003-1564/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2003-1564
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2003-1564
- OSV: https://osv.dev/vulnerability/CVE-2003-1564

---
From sbomify Insights: https://insights.sbomify.com/CVE-2003-1564/
Summaries are generated and may contain mistakes; the official description above is the record.