VulnerabilityAnalyzed

CVE-2026-27613

A vulnerability in versions prior to 2.01 allows unauthenticated remote attackers to bypass the web server's CGI parameter security controls.

CRITICAL 10.0EPSS 0.75%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (0.75%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

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`).

CVSS 4.0: 10.0 CRITICALCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
EPSS: 0.75% probability · 53th percentile
CISA KEV: Not listed
Weakness: CWE-78, CWE-88
Affected: ritlabs/tinyweb
Source: security-advisories@github.com

References

https://github.com/maximmasiutin/TinyWeb/commit/d9dbda8db49da69d2160e1c527e782b73b5ffb6bPatch
https://github.com/maximmasiutin/TinyWeb/releases/tag/v2.01Release Notes
https://github.com/maximmasiutin/TinyWeb/security/advisories/GHSA-rfx5-fh9m-9jj9Vendor Advisory
https://www.masiutin.net/tinyweb-cve-2026-27613.htmlThird Party Advisory

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.