Ultimate Sitemap Parser (USP): XML Entity Expansion (Billion Laughs) DoS in XMLSitemapParser

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

XML Entity Expansion (Billion Laughs) DoS in XMLSitemapParser Summary ultimate-sitemap-parser version 1.8.0 and earlier parse attacker-controlled XML content using Python's xml.parsers.expat without any restriction on DTD declarations or recursive entity references. An attacker who can serve a malicious sitemap can trigger exponential XML entity expansion (the "Billion Laughs" attack), causing unbounded CPU and memory consumption in the victim process. No authentication, user interaction, or special configuration is required — the vulnerability is exploitable by default through any public-facing use of sitemaptreeforhomepage() or sitemapfromstr(). Details The vulnerable code path begins at the public API entry points and flows to the Expat XML parser without any sanitization: 1. usp/tree.py:42 — sitemaptreeforhomepage(homepageurl) is the primary public entry point. 2. usp/tree.py:133 — sitemapfromstr(content) is the secondary public entry point (also directly reachable from user…

Published by the source

19 Jun 2026, 21:15 UTC

Last modified by the source

19 Jun 2026, 21:30 UTC

Source last checked

26 Oct 2026, 13:46 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-p5wc-9w9r-m232

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-p5wc-9w9r-m232

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# Patch Next advisory brief: GHSA-p5wc-9w9r-m232

Advisory: Ultimate Sitemap Parser (USP): XML Entity Expansion (Billion Laughs) DoS in XMLSitemapParser
IDs: GHSA-p5wc-9w9r-m232
Record: https://patchnext.com/advisories/ghsa-p5wc-9w9r-m232 (revision 2, source checked 26 Oct 2026, 13:46 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: ultimate-sitemap-parser 1.8.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI ultimate-sitemap-parser: affected <= 1.8.0; fixed in 1.8.1

## Suggested inspection (read-only)
- `python -m pip show ultimate-sitemap-parser`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on ultimate-sitemap-parser.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-p5wc-9w9r-m232 (OSV record GHSA-p5wc-9w9r-m232 lists affected ranges: PyPI ultimate-sitemap-parser >=0 <1.8.1 (fixed))
- Verified: https://github.com/advisories/GHSA-p5wc-9w9r-m232 (GitHub-reviewed advisory GHSA-p5wc-9w9r-m232 lists affected ranges: PyPI ultimate-sitemap-parser >=0 <=1.8.0)

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