vulnerability / NVI-00018587 / Revision 1
FastFeedParser has an infinite redirect loop DoS via meta-refresh chain
GitHub lists this reviewed advisory for fastfeedparser. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
7.5 high
GitHub source severity; exploitability and local consequence require separate evidence.
As of · GitHub Advisory Database
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
fastfeedparser
source listed<= 0.5.9
### Summary 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. ### Details `parse()` catches `ValueError` on XML parse failure, extracts a meta-refresh URL from the HTML response via `_extract_meta_refresh_url()`, and tail-calls itself with that URL. The recursive call is unconditional — there is no maximum redirect depth, no set of already-visited URLs, and no guard against self-referential or looping redirects. **`fastfeedparser/main.py` — `parse()` (recursive sink):** ```python def parse(source: str | bytes, ...) -> FastFeedParserDict: is_url = isinstance(source, str) and source.startswith(("http://", "https://")) if is_url: content = _fetch_url_content(source) t
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database
A fixed release is not deployment evidence.
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04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
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- GHSA-4gx2-pc4f-wq37 ↗
GitHub Advisory Database · vendor advisory
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Public revision history
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- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.