Incorrect Comparison in Mongoose - CVE-2026-73258
Published: August 12, 2026
Vulnerability identifier: #VU142186
CSH Severity: Medium
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-73258
CWE-ID: CWE-697
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to bypass Content-Type-based security filters and corrupt multipart header parsing.
The vulnerability exists due to incorrect comparison in mg_http_next_multipart() when parsing multipart form-data headers and boundaries. A remote attacker can send a specially crafted multipart request to bypass Content-Type-based security filters and corrupt multipart header parsing.
The issue can be triggered by embedding a lone carriage return in a multipart header, which can truncate header values, corrupt filenames, or misidentify boundary lines.
Affected software
Mongoose
How to mitigate CVE-2026-73258
Install security update from vendor's website.
Mongoose - update to 7.22