Vulnerability · Published Aug 20, 2026 · Assigned by GitHub_M

CVE-2026-73255Mongoose: Path traversal in SSI #include directives enables arbitrary file read

Medium 6.5

In plain English

A medium-severity path traversal in mongoose from cesanta. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.7% (higher than 52% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)6.5Medium

Exploit odds (30 days)0.7%top 48.4% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

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 packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Debian:14	mongoose	7.22+ds-1	DEBIAN-CVE-2026-73255
Ubuntu:26.10	mongoose	no fix listed	UBUNTU-CVE-2026-73255

Affected products (as reported)

Vendor	Product	Versions
cesanta	mongoose	< 7.22

Weakness: CWE-22 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

References

https://github.com/cesanta/mongoose/security/advisories/GHSA-h7m9-764r-7x4x x_refsource_CONFIRM
https://github.com/cesanta/mongoose/pull/3611 x_refsource_MISC
https://github.com/cesanta/mongoose/commit/a9df523f76f43a38bd53b4232b9cfd4c16869e71 x_refsource_MISC
https://github.com/cesanta/mongoose/releases/tag/7.22 x_refsource_MISC