CVE-2026-39376
FastFeedParser has an infinite redirect loop DoS via meta-refresh chain
Description
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.
INFO
Published Date :
April 7, 2026, 8:16 p.m.
Last Modified :
April 14, 2026, 8:12 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | [email protected] |
Solution
- Update FastFeedParser to version 0.5.10.
- Avoid parsing untrusted URLs if possible.
- Implement depth and redirect limits.
Public PoC/Exploit Available at Github
CVE-2026-39376 has a 3 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-39376.
| URL | Resource |
|---|---|
| https://github.com/kagisearch/fastfeedparser/security/advisories/GHSA-4gx2-pc4f-wq37 | Exploit Vendor Advisory |
| https://github.com/kagisearch/fastfeedparser/security/advisories/GHSA-4gx2-pc4f-wq37 | Exploit Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-39376 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-39376
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
CVE-2026-39376(Infinite redirect loop DoS via meta-refresh chain)
None
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The following list is the news that have been mention
CVE-2026-39376 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-39376 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Apr. 14, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:kagi:fastfeedparser:*:*:*:*:*:python:*:* versions up to (excluding) 0.5.10 Added Reference Type CISA-ADP: https://github.com/kagisearch/fastfeedparser/security/advisories/GHSA-4gx2-pc4f-wq37 Types: Exploit, Vendor Advisory Added Reference Type GitHub, Inc.: https://github.com/kagisearch/fastfeedparser/security/advisories/GHSA-4gx2-pc4f-wq37 Types: Exploit, Vendor Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Apr. 08, 2026
Action Type Old Value New Value Added Reference https://github.com/kagisearch/fastfeedparser/security/advisories/GHSA-4gx2-pc4f-wq37 -
New CVE Received by [email protected]
Apr. 07, 2026
Action Type Old Value New Value Added Description 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. Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Added CWE CWE-674 Added Reference https://github.com/kagisearch/fastfeedparser/security/advisories/GHSA-4gx2-pc4f-wq37