CVE-2026-73258 PUBLISHED

Mongoose: Multipart boundary/header scan logic error in mg_http_next_multipart

Assigner: GitHub_M
Reserved: 11.08.2026 Published: 20.08.2026 Updated: 20.08.2026

Mongoose is an embedded web server and network library. Prior to 7.22, a remote attacker can place a lone carriage return or line feed in multipart input processed by mg_http_next_multipart() in src/http.c. The loops comparing s[b] and s[b + 1], and s[h2] and s[h2 + 1], use an incorrect AND condition and stop when either character resembles part of a CRLF terminator. This truncates headers, filenames, or boundaries and can cause an application to accept dangerous content after seeing a misleading Content-Type value. This issue is fixed in version 7.22.

Metrics

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
CVSS Score: 6.5

Product Status

Vendor cesanta
Product mongoose
Versions
  • Version < 7.22 is affected

References

Problem Types

  • CWE-697: Incorrect Comparison CWE