CVE-2026-73256

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.

Affected Software

VendorProductVersion RangeStatus
cesantamongoose< 7.22affected

Weaknesses

  • CWE-444: CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

References