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CVE-2026-39376GHSA-4GX2-PC4F-WQ37PYSEC-2026-60

FastFeedParser has an infinite redirect loop DoS via meta-refresh chain

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 0.5.10
1 proof of concept on GitHub
  • Exploitation: poc
  • Automatable: yes
  • Technical impact: partial

Summary

FastFeedParser is a high performance RSS, Atom and RDF parser. Prior to 0.5.10, when parse() fetches a URL that returns an HTML page containing a <meta http-equiv="refresh"> tag, it recursively calls itself with the redirect URL — with no depth limit, no visited-URL deduplication, and no redirect count cap. An attacker-controlled server that returns an infinite chain of HTML meta-refresh responses causes unbounded recursion, exhausting the Python call stack and crashing the process. This vulnerability can also be chained with the companion SSRF issue to reach internal network targets after bypassing the initial URL check. This vulnerability is fixed in 0.5.10.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: poc · Automatable: yes · Technical impact: partial

  3. Record last updated

Affected versions

  • kagisearch fastfeedparser

    fixed in 0.5.10

  • fastfeedparserPyPI

    fixed in 0.5.10

References 2

GitHub · kagisearch/fastfeedparser

GitHub · redyank/CVE-2026-39376