CVE-2026-73256 (GCVE-0-2026-73256)
Vulnerability from cvelistv5 – Published: 2026-08-20 17:37 – Updated: 2026-08-21 21:46
VLAI
EPSS
VEX
Title
Mongoose: HTTP/1.0 detection off-by-one enables request smuggling via chunked TE
Summary
Mongoose is an embedded web server and network library. Prior to 7.22, a remote unauthenticated attacker can exploit an HTTP/1.0 reverse-proxy deployment by sending a request with Transfer-Encoding: chunked and conflicting framing. The http_cb() function in src/http.c tests hm.proto.len with an impossible greater-than-eight condition even though mg_http_parse() requires an eight-byte protocol string, so is_http_1_0 is never set. Mongoose consequently processes chunked encoding that an HTTP/1.0 proxy can ignore, enabling request smuggling and unauthorized access or state changes. This issue is fixed in version 7.22.
Severity
9.1 (Critical)
SSVC
Exploitation: none
Automatable: yes
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-21 21:10 UTC
CWE
- CWE-444 - Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
Assigner
References
4 references
| URL | Tags |
|---|---|
| https://github.com/cesanta/mongoose/security/advi… | x_refsource_CONFIRM |
| https://github.com/cesanta/mongoose/pull/3611 | x_refsource_MISC |
| https://github.com/cesanta/mongoose/commit/a9df52… | x_refsource_MISC |
| https://github.com/cesanta/mongoose/releases/tag/7.22 | x_refsource_MISC |
Impacted products
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