Eventlet is a concurrent networking library for Python. Prior to version 0.40.3, the Eventlet WSGI parser is vulnerable to HTTP Request Smuggling due to improper handling of HTTP trailer sections. This vulnerability could enable attackers to, bypass front-end security controls, launch targeted attacks against active site users, and poison web caches. This problem has been patched in Eventlet 0.40.3 by dropping trailers which is a breaking change if a backend behind eventlet.wsgi proxy requires trailers. A workaround involves not using eventlet.wsgi facing untrusted clients.
Fix
Patch, vendor advisory and mitigation references on NVD 2
- https://github.com/eventlet/eventlet/commit/0bfebd1117d392559e25b4bfbfcc941754de88fb Patch
- https://github.com/eventlet/eventlet/security/advisories/GHSA-hw6f-rjfj-j7j7 Vendor Advisory
Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.
Change history 1
- First seenCVSS 6.3 · eventletNVD modified 2026-10-19 17:10
Affected (CPE criteria) 1
cpe:2.3:a:eventlet:eventlet:*:*:*:*:*:*:*:*
References 4
- https://github.com/eventlet/eventlet/commit/0bfebd1117d392559e25b4bfbfcc941754de88fb Patch
- https://github.com/eventlet/eventlet/pull/1062 Issue Tracking
- https://github.com/eventlet/eventlet/security/advisories/GHSA-hw6f-rjfj-j7j7 Vendor Advisory
- https://lists.debian.org/debian-lts-announce/2025/09/msg00003.html