CVE-2026-73257: cesanta mongoose

CVSS 9.1 (critical) · published 2026-08-20

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.

Affected products (NVD): cesanta mongoose

Fixed in (NVD): 7.22

Weakness: CWE-444

Source: NVD CVE-2026-73257

References

• https://github.com/cesanta/mongoose/commit/a9df523f76f43a38bd53b4232b9cfd4c16869e71
• https://github.com/cesanta/mongoose/pull/3611
• https://github.com/cesanta/mongoose/releases/tag/7.22
• https://github.com/cesanta/mongoose/security/advisories/GHSA-5wfq-r6mr-wqp6
• https://github.com/cesanta/mongoose/security/advisories/GHSA-5wfq-r6mr-wqp6

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