CVE-2026-73257

Mongoose is an embedded web server and network library. Priro to version 7.22, a remote unauthenticated attacker can send an HTTP request containing both Content-Length and Transfer-Encoding: chunked. The cl_count and te_count checks in the mg_http_parse() and http_cb() paths in src/http.c accept both headers and prioritize chunked encoding, while a Content-Length-preferring reverse proxy can use a different request boundary. This CL.TE desynchronization can inject requests that access or modify resources in another user context. This issue is fixed in version 7.22.

• CWE-444

• https://github.com/cesanta/mongoose/commit/a9df523f76f43a38bd53b4232b9cfd4c16869e71Patch
• https://github.com/cesanta/mongoose/pull/3611Issue Tracking, Patch
• https://github.com/cesanta/mongoose/releases/tag/7.22Release Notes
• https://github.com/cesanta/mongoose/security/advisories/GHSA-5wfq-r6mr-wqp6Exploit, Vendor Advisory
• https://github.com/cesanta/mongoose/security/advisories/GHSA-5wfq-r6mr-wqp6Exploit, Vendor Advisory

Published

Aug 20, 2026

Last Modified

Oct 18, 2026

Status

Analyzed

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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