Medium severity · published Aug 20, 2026
CVE-2026-73255
Mongoose: Path traversal in SSI #include directives enables arbitrary file read
6.5
CVSS
0.7%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
High
Integrity
None
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.7% · higher than 51% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
MO
mongoose · cesanta
< 7.22 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-73255
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-73255
Patch
https://github.com/cesanta/mongoose/commit/a9df523f76f43a38bd53b4232b9cfd4c16869e71
Issue Tracking
https://github.com/cesanta/mongoose/pull/3611
Release Notes
https://github.com/cesanta/mongoose/releases/tag/7.22
Exploit
https://github.com/cesanta/mongoose/security/advisories/GHSA-h7m9-764r-7x4x
More from mongoose
9.8
CVE-2026-5244
Cesanta Mongoose TLS 1.3 mongoose.c mg_tls_recv_cert heap-based overflow
9.8
CVE-2024-42383
Use of Out-of-range Pointer Offset vulnerability in Cesanta Mongoose Web Server v7.14 allows to write a NULL byte value beyond the memory space dedicated for the hostname field
9.8
CVE-2020-25756
A buffer overflow vulnerability exists in the mg_get_http_header function in Cesanta Mongoose 6.18 due to a lack of bounds checking
9.8
CVE-2019-19307
An integer overflow in parse_mqtt in mongoose.c in Cesanta Mongoose 6.16 allows an attacker to achieve remote DoS (infinite loop), or possibly cause an out-of-bounds write, by…
9.8
CVE-2019-12951
An issue was discovered in Mongoose before 6.15