---
id: CVE-2020-5227
aliases:
  - GHSA-g8q7-xv52-hf9f
  - PYSEC-2020-231
title: Feedgen Vulnerable to XML Denial of Service Attacks
summary: Feedgen Vulnerable to XML Denial of Service Attacks
severity: medium
cvss: 4.4
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H'
vendor: feedgen
product: feedgen
ecosystem: pip
affected:
  - feedgen < 0.9.0
patched:
  - feedgen 0.9.0
published: '2020-01-28'
updated: '2026-07-08'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-g8q7-xv52-hf9f'
references:
  - url: >-
      https://github.com/lkiesow/python-feedgen/security/advisories/GHSA-g8q7-xv52-hf9f
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2020-5227'
  - url: >-
      https://github.com/lkiesow/python-feedgen/commit/f57a01b20fa4aaaeccfa417f28e66b4084b9d0cf
  - url: >-
      https://docs.microsoft.com/en-us/archive/msdn-magazine/2009/november/xml-denial-of-service-attacks-and-defenses
  - url: 'https://github.com/lkiesow/python-feedgen'
  - url: >-
      https://github.com/pypa/advisory-database/tree/main/vulns/feedgen/PYSEC-2020-231.yaml
  - url: >-
      https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/T6I5ENUYGFNMIH6ZQ62FZ6VU2WD3SIOI
tags:
  - osv
  - pip
epss: 0.02182
epssPercentile: 0.81606
ingestedAt: '2026-07-08T18:25:49.676Z'
---

## Overview

### Impact

The *feedgen* library allows supplying XML as content for some of the available fields. This XML will be parsed and integrated into the existing XML tree. During this process, feedgen is vulnerable to [XML Denial of Service Attacks](https://docs.microsoft.com/en-us/archive/msdn-magazine/2009/november/xml-denial-of-service-attacks-and-defenses) (e.g. XML Bomb).

This becomes a concern in particular if feedgen is used to include content from untrused sources and if XML (including XHTML) is directly included instead of providing plain tex content only.

### Patches

This problem has been fixed in feedgen 0.9.0 which disallows XML entity expansion and external resources.

### Workarounds

Updating is strongly recommended and should not be problematic. Nevertheless, as a workaround, avoid providing XML directly to feedgen or ensure that no entity expansion is part of the XML. 

### References

- [Security Briefs - XML Denial of Service Attacks and Defenses](https://docs.microsoft.com/en-us/archive/msdn-magazine/2009/november/xml-denial-of-service-attacks-and-defenses)
- [Billion laughs attack](https://en.wikipedia.org/wiki/Billion_laughs_attack#cite_note-2)

### For more information

If you have any questions or comments about this advisory:
- Open an issue in [lkiesow/python-feedgen](https://github.com/lkiesow/python-feedgen/issues)
- Send an email to security@lkiesow.de

## Affected packages

- `feedgen < 0.9.0`

## Remediation

Upgrade to a patched release:

- `feedgen 0.9.0`