CVE-2026-73256
CriticalCVSS 9.1Summary
A vulnerability in Mongoose before version 7.22 allows a remote unauthenticated attacker to exploit an HTTP/1.0 reverse-proxy deployment by sending a request with Transfer-Encoding: chunked and conflicting framing. The http_cb() function tests hm.proto.len with an impossible greater-than-eight condition, so is_http_1_0 is never set, and Mongoose processes chunked encoding that an HTTP/1.0 proxy can ignore.
Risk Assessment
The risk includes request smuggling and unauthorized access or state changes, potentially leading to security breaches.
Recommendation
Upgrade Mongoose to version 7.22 or later, which includes the fix.
Original NVD description (English source)
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.