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CVE-2026-73256

CVE-2026-73256 · Mongoose: HTTP/1.0 detection off-by-one enables request smuggling via chunked TE

This page contains facts from public vulnerability sources. Check the original advisory before updating.

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 9.1 · Critical · EPSS 0.4% · Fix available

Published
Updated

Stack: system

Affected products and versions

  • mongoose

    Versions
    • < 7.22: Affected

    No fix published

  • mongoose Debian:14

    Versions
    • 7.21+ds-1
    • 7.21+ds-1~bpo13+1
    • 7.21+ds-2
    • 7.22+ds-1~bpo13+1
    Affected ranges
    • ECOSYSTEM: < 7.22+ds-1

    Update to 7.22+ds-1

  • mongoose Ubuntu:26.10

    Versions
    • 7.21+ds-1
    • 7.21+ds-2
    • 7.22+ds-1
    • 7.23+ds-1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

Original sources

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