kagisearch fastfeedparser up to 0.5.9 RDF Parser parse recursion

Summaryinfo

A vulnerability categorized as problematic has been discovered in kagisearch fastfeedparser up to 0.5.9. Affected by this vulnerability is the function parse of the component RDF Parser. Such manipulation leads to recursion. This vulnerability is documented as CVE-2026-39376. The attack can be executed remotely. There is not any exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in kagisearch fastfeedparser up to 0.5.9. Affected by this issue is the function parse of the component RDF Parser. The manipulation with an unknown input leads to a recursion vulnerability. Using CWE to declare the problem leads to CWE-674. The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack. Impacted is availability. CVE summarizes:

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 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.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-39376 since 04/06/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1499.

Upgrading to version 0.5.10 eliminates this vulnerability.

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Productinfo

Vendor

• kagisearch

Name

• fastfeedparser

Version

• 0.5.0
• 0.5.1
• 0.5.2
• 0.5.3
• 0.5.4
• 0.5.5
• 0.5.6
• 0.5.7
• 0.5.8
• 0.5.9

Website

• Product: https://github.com/kagisearch/fastfeedparser/

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