CVE-2026-73256 (GCVE-0-2026-73256)

Vulnerability from cvelistv5 – Published: 2026-08-20 17:37 – Updated: 2026-08-20 17:37
VLAI
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)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CWE
  • CWE-444 - Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
Assigner
References
Impacted products
Vendor Product Version CPE status
cesanta mongoose Affected: < 7.22
guessed Create a notification for this product.
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      ],
      "problemTypes": [
        {
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            {
              "cweId": "CWE-444",
              "description": "CWE-444: Inconsistent Interpretation of HTTP Requests (\u0027HTTP Request/Response Smuggling\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
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      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-20T17:37:54.505Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/cesanta/mongoose/security/advisories/GHSA-mgp5-rjrv-h5j3",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/cesanta/mongoose/security/advisories/GHSA-mgp5-rjrv-h5j3"
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        {
          "name": "https://github.com/cesanta/mongoose/releases/tag/7.22",
          "tags": [
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          ],
          "url": "https://github.com/cesanta/mongoose/releases/tag/7.22"
        }
      ],
      "source": {
        "advisory": "GHSA-mgp5-rjrv-h5j3",
        "discovery": "UNKNOWN"
      },
      "title": "Mongoose: HTTP/1.0 detection off-by-one enables request smuggling via chunked TE"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-73256",
    "datePublished": "2026-08-20T17:37:54.505Z",
    "dateReserved": "2026-08-11T17:18:01.598Z",
    "dateUpdated": "2026-08-20T17:37:54.505Z",
    "state": "PUBLISHED"
  },
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  }
}



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