Authorization bypass via chunked trailer request smuggling
Published Sep 25, 2023 · Updated Nov 25, 2025
HTTP request smuggling in gevent.pywsgi before 23.9.0 allows remote attackers to bypass upstream access controls with chunked requests. The WSGI server accepts invalid HTTP chunk trailers and treats an embedded request line as a second request on the same keep-alive connection. Exploitation requires an upstream server that forwards invalid trailers without validation and relies on path or header filtering; the smuggled request can reach protected application routes.
Summary
What happened
HTTP request smuggling in gevent.pywsgi before 23.9.0 allows remote attackers to bypass upstream access controls with chunked requests. The WSGI server accepts invalid HTTP chunk trailers and treats an embedded request line as a second request on the same keep-alive connection. Exploitation requires an upstream server that forwards invalid trailers without validation and relies on path or header filtering; the smuggled request can reach protected application routes.
The record
- CVE
- CVE-2023-41419
- Published
- Sep 25, 2023
- Updated
- Nov 25, 2025
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 25, 2023CVE publishedPublication date reported by the CVE source.
- Nov 25, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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What conditions does exploitation require?
What is affected?
Affected products and versions are unavailable in this record.
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Invalid chunk-trailer request-smuggling payloadproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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