CVE-2026-27613: CGI Parameter Injection (Bypass of STRICT_CGI_PARAMS and EscapeShellParam)
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 STRICTCGIPARAMS 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).
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
TinyWebto a version that resolves this vulnerability.Fixed in 2.01 - Configuration
Ensure STRICT_CGI_PARAMS is enabled; it is defined by default in define.inc.
TinyWeb STRICT_CGI_PARAMS = enabled - Configuration
Do not use CGI executables that natively accept dangerous command-line flags, such as php-cgi.exe.
TinyWeb CGI execution CGI executable selection = do not use CGI executables that natively accept dangerous command-line flags - Compensating control
If hosting PHP, place TinyWeb behind a Web Application Firewall (WAF) that explicitly blocks URL query-string parameters beginning with '-' or containing encoded double quotes (%22).
Event History
Frequently Asked Questions
What is the severity of CVE-2026-27613?
CVE-2026-27613 is considered a high severity vulnerability due to its potential impact on server security.
How do I fix CVE-2026-27613?
To fix CVE-2026-27613, upgrade TinyWeb to version 2.01 or later.
What types of attacks does CVE-2026-27613 allow?
CVE-2026-27613 allows unauthenticated remote attackers to bypass the web server's CGI parameter security controls.
Which versions of TinyWeb are affected by CVE-2026-27613?
TinyWeb versions prior to 2.01 are affected by CVE-2026-27613.
What components of TinyWeb does CVE-2026-27613 impact?
CVE-2026-27613 impacts the CGI executable functionality of the TinyWeb server.