CVE-2026-73255: Cesanta Mongoose

Medium severity, CVSS 6.5. EPSS: 0.7% chance of exploitation in the next 30 days.

Mongoose is an embedded web server and network library. Prior to 7.22, an attacker who can control an SSI-enabled file can place directory traversal sequences in an #include file or #include virtual directive. The mg_ssi() function in src/ssi.c concatenates the directive argument into a filesystem path without calling mg_path_is_sane(), allowing an MG_ENABLE_SSI deployment with ssi_pattern configured to disclose files readable by the Mongoose process. This issue is fixed in version 7.22.

Affected products

• Cesanta Mongoose: before 7.22 (fixed in 7.22)

Published 2026-08-20. Last modified 2026-09-29.