CVE-2026-27613 CGI Parameter Injection (Bypass of STRICT_CGI_PARAMS and EscapeShellParam)
Unauthenticated attackers can bypass CGI security controls in TinyWeb to achieve remote code execution or source code disclosure.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-27613?
CVE-2026-27613 is a critical command injection vulnerability in maximmasiutin TinyWeb, published on 25 Feb 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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`).
Which versions are affected by CVE-2026-27613?
It affects 1 product.
Products include Ritlabs Tinyweb.
How do I fix CVE-2026-27613?
No fix has been published for CVE-2026-27613 yet. Limit exposure of the affected software until one is available.
Upgrade, and pass arguments to programs as a list instead of through a shell. More about Command injection.
Is CVE-2026-27613 being exploited?
There is no known exploitation of CVE-2026-27613 in the wild and no public exploit code.
Other vulnerabilities in maximmasiutin TinyWeb
- CVE-2026-22781 TinyWeb CGI Command Injection
- CVE-2026-28497 TinyWeb: Integer Overflow in `_Val` (HTTP Request Smuggling)
- CVE-2026-29046 TinyWeb: HTTP Header Control Character Injection into CGI Environment
- CVE-2026-27630 TinyWeb vulnerable to Remote Denial of Service via Thread/Connection Exhaustion (Slowloris)
- CVE-2026-27633 TinyWeb has Unbounded Content-Length Memory Exhaustion (DoS)
Sources
Also known as GHSA-rfx5-fh9m-9jj9.