Vulnerability Details CVE-2026-39376
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.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.001
EPSS Ranking 16.3%
CVSS Severity
CVSS v3 Score 7.5
References
Products affected by CVE-2026-39376
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cpe:2.3:a:kagi:fastfeedparser:*