CVE-2026-73256
criticalpriority · track · 0EPSS 0.004 · 38 %ileRUUSEPSS · scored 2026-10-27
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.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · high–critical · 8.3–9.1
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
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affected products (2)
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also known as (2)
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sources
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references (4) nvd
External citations — patches, advisories, analysis.
- https://github.com/cesanta/mongoose/commit/a9df523f76f43a38bd53b4232b9cfd4c16869e71Patch
- https://github.com/cesanta/mongoose/pull/3611Issue TrackingPatch
- https://github.com/cesanta/mongoose/releases/tag/7.22Release Notes
- https://github.com/cesanta/mongoose/security/advisories/GHSA-mgp5-rjrv-h5j3ExploitVendor Advisory
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