EUVD-2026-9972

Comprehensive Technical Analysis of EUVD-2026-9972

1. Vulnerability Assessment and Severity Evaluation

The vulnerability in TinyWeb, a web server written in Delphi for Win32, pertains to its handling of request header values. Prior to version 2.04, TinyWeb did not adequately sanitize dangerous control characters (CR, LF, NUL) and their encoded forms (%0d, %0a, %00) in header lines and values. This oversight can lead to header value confusion across parser boundaries, potentially creating unsafe data in the CGI execution context.

Severity Evaluation:

• Base Score: 9.2
• Base Score Version: 4.0
• Base Score Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:L/SC:N/SI:H/SA:L

The high base score indicates a critical vulnerability. The attack vector (AV:N) is network-based, requiring low attack complexity (AC:L) and no privileges (PR:N) or user interaction (UI:N). The vulnerability has a high impact on integrity (VI:H) and availability (VA:L), with a significant impact on system integrity (SI:H).

2. Potential Attack Vectors and Exploitation Methods

Attack Vectors:

• HTTP Request Header Injection: An attacker can inject malicious control characters into HTTP request headers, which are then improperly parsed and mapped into CGI environment variables.
• Header Value Confusion: By exploiting the lack of strict rejection of dangerous control characters, an attacker can create confusion across parser boundaries, leading to potential command injection or other forms of data manipulation.

Exploitation Methods:

• Command Injection: An attacker could inject commands into the CGI environment variables, potentially leading to arbitrary code execution.
• Data Manipulation: Malicious actors could manipulate data in the CGI execution context, leading to unauthorized actions or data corruption.

3. Affected Systems and Software Versions

Affected Systems:

• TinyWeb web server versions prior to 2.04.

Software Versions:

• All versions of TinyWeb before 2.04 are vulnerable.

4. Recommended Mitigation Strategies

Immediate Actions:

• Upgrade: Upgrade to TinyWeb version 2.04 or later, which includes the patch for this vulnerability.
• Input Validation: Implement strict input validation and sanitization for all HTTP request headers to reject dangerous control characters.

Long-Term Strategies:

• Regular Patching: Ensure that all web servers and related software are regularly updated with the latest security patches.
• Security Audits: Conduct regular security audits and vulnerability assessments to identify and mitigate potential vulnerabilities.
• Web Application Firewalls (WAF): Deploy WAFs to monitor and filter malicious HTTP requests.

5. Impact on European Cybersecurity Landscape

The vulnerability in TinyWeb highlights the importance of robust input validation and sanitization in web server software. Given the widespread use of web servers in various industries, this vulnerability underscores the need for vigilant cybersecurity practices. The European cybersecurity landscape must prioritize regular updates, thorough security audits, and the implementation of advanced security measures to protect against such vulnerabilities.

6. Technical Details for Security Professionals

Vulnerability Details:

• Parser Issue: The parser in TinyWeb versions prior to 2.04 does not strictly reject dangerous control characters in header lines and values.
• Encoded Forms: The parser also fails to defend against encoded forms of control characters such as %0d, %0a, and %00.
• CGI Environment Variables: The improperly sanitized header values are mapped into CGI environment variables, creating potential security risks.

References:

• GitHub Advisory: GHSA-r3gf-pg2c-m7mc
• Patch Commit: 53aa8b6e5146491d7be57920e3fc50d7a34e4d5a

Aliases:

• CVE ID: CVE-2026-29046

Assigner:

• GitHub_M

ENISA IDs:

• Product: [{"id":"164ff331-db02-3830-9fe8-56baaa7ee0fc","product":{"name":"TinyWeb"},"product_version":"< 2.04"}]
• Vendor: [{"id":"fe0b9c7a-48ad-3092-b00d-f2a66f615fa2","vendor":{"name":"maximmasiutin"}}]

By addressing this vulnerability promptly and implementing robust security measures, organizations can significantly reduce the risk of exploitation and ensure the integrity and availability of their web services.