Raw vector
CVSS: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/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:XSummary
CVE-2026-27613 is a critical-severity OS Command Injection (CWE-78) vulnerability in Ritlabs Tinyweb. Its CVSS base score is 10.0 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Command and Scripting Interpreter (T1059); ranked in the top 48% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-27613 is a vulnerability in TinyWeb, a web server supporting HTTP and HTTPS written in Delphi for Win32 platforms, affecting versions prior to 2.01. The flaw enables unauthenticated remote attackers to bypass the web server's CGI parameter security controls, stemming from issues classified under CWE-78 (OS Command Injection) and CWE-88 (Improper Neutralization of Argument Delimiters). It carries a CVSS v3.1 base score of 9.8 (Critical), reflecting network accessibility with low complexity and no privileges required.
Attackers can exploit this vulnerability remotely without authentication by crafting malicious requests that manipulate CGI parameters. Depending on the server configuration and the specific CGI executable deployed—particularly interpreted languages like PHP—the impact ranges from source code disclosure to remote code execution (RCE). Organizations hosting CGI scripts on vulnerable TinyWeb instances are at risk, with php-cgi.exe highlighted as especially susceptible due to its acceptance of dangerous command-line flags.
The vulnerability has been addressed in TinyWeb version 2.01, as detailed in the project's GitHub release and commit history. For those unable to upgrade immediately, mitigations include verifying that the STRICT_CGI_PARAMS directive is enabled (it is defined by default in define.inc), avoiding CGI executables that accept hazardous command-line flags, and for PHP deployments, positioning the server behind a Web Application Firewall (WAF) configured to block URL query string parameters starting with a hyphen (-) or containing encoded double quotes (%22). Additional guidance is available in the GitHub security advisory and related documentation.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-8763
Vulnerability Data
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…
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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`).
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V1.2.5V1.2.8V15.2.5
Mitigating Controls (NIST 800-53 r5) AI
Developer testing and evaluation can discover missing or incorrect command sanitization during development.
Input validation directly neutralizes or rejects special characters that would otherwise alter OS command structure.
Least privilege reduces the permissions available to any process that could be subverted by injected commands.
Least functionality restricts available OS commands and interpreters, limiting the blast radius of injection.
Secure engineering principles require proper neutralization of untrusted input before command construction.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
PR.PS-06's SDLC practices directly require secure coding and input handling that blocks command-injection defects, yet the single broad outcome leaves many specific neutralization vectors and verification gaps unaddressed.
Routine patching/maintenance can remediate known command-injection CVEs in dependencies (partial forward) but does nothing to stop developers from introducing improper neutralization in custom code (none reverse).
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing and code review target insecure use of operating-system command interfaces, catching command-injection flaws introduced during development.
Secure development lifecycle mandates input validation and command construction practices that directly prevent argument injection.
Application security requirements include explicit rules for safe command-line argument handling and escaping.
Secure architecture principles discourage unsafe command invocation patterns and favor safer APIs.
Secure coding standards explicitly require proper neutralization of command arguments, directly eliminating CWE-88.
Change management can catch unsafe command patterns during reviews but is not a direct mitigation.