CVE-2026-29046 TinyWeb: HTTP Header Control Character Injection into CGI Environment

Critical 9.2 Published 6 Mar 2026 Updated 6 Mar 2026

Attackers can inject control characters into HTTP headers to manipulate CGI environment variables, potentially leading to code execution in TinyWeb.

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-2026-29046?

CVE-2026-29046 is a critical code injection vulnerability in maximmasiutin TinyWeb, published on 6 Mar 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. Prior to version 2.04, TinyWeb accepts request header values and later maps them into CGI environment variables (HTTP_*). The parser did not strictly reject dangerous control characters in header lines and header values, including CR, LF, and NUL, and did not consistently defend against encoded forms such as %0d, %0a, and %00. This can enable header value confusion across parser boundaries and may create unsafe data in the CGI execution context. This issue has been patched in version 2.04.

Weakness: CWE-93, CWE-74, CWE-20, CWE-114

Which versions are affected by CVE-2026-29046?

It affects 1 product.

Products include Ritlabs Tinyweb.

How do I fix CVE-2026-29046?

No fix has been published for CVE-2026-29046 yet. Limit exposure of the affected software until one is available.

Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.

Is CVE-2026-29046 being exploited?

There is no known exploitation of CVE-2026-29046 in the wild and no public exploit code.

Sources

Also known as GHSA-r3gf-pg2c-m7mc.