RCE in Maximmasiutin Tinyweb
CVE-2026-27613
TinyWeb is a web server (HTTP, HTTPS) written in Delphi for Win32. A vulnerability in versions prior to 2.01 allows unauthenticated remote attackers to bypass the web server's CGI parameter security controls. Depending on the server configuration and the specific CGI executable in use, the impact is either source code disclosure or remote code execution (RCE). Anyone hosting CGI scripts (particularly interpreted languages like PHP) using vulnerable versions of TinyWeb is impacted. The problem has been patched in version 2.01. If upgrading is not immediately possible, ensure `STRICT_CGI_PARAMS` is enabled (it is defined by default in `define.inc`) and/or do not use CGI executables that natively accept dangerous command-line flags (such as `php-cgi.exe`). If hosting PHP, consider placing the server behind a Web Application Firewall (WAF) that explicitly blocks URL query string parameters that begin with a hyphen (`-`) or contain encoded double quotes (`%22`).
Vulnerability class: Command Injection (OS Command Injection)
EPSS: 0.007 (52.5th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
Affected products
- Maximmasiutin Tinyweb — versions < 2.01
- Ritlabs Tinyweb
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Vendor Advisory)
- security-advisories@github.com (Patch, x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC, Release Notes)
- security-advisories@github.com (Third Party Advisory, x_refsource_MISC)
Frequently asked questions
- What is CVE-2026-27613?
- CVE-2026-27613 is a critical-severity vulnerability in Maximmasiutin Tinyweb, classified under OS Command Injection. CVSS score: 9.8/10. Published 2026-02-25.
- How severe is CVE-2026-27613?
- Critical severity. CVSS v3 base score is 9.8 out of 10.