TIM Flow before 26.0.6 CRLF Injection Vulnerability

Executive Summary

TIM Flow before version 26.0.6 has a CRLF injection flaw. Attackers can inject unsanitized carriage return and line feed sequences into the rt URL parameter and access_token cookie. These sequences are reflected into Set-Cookie response headers, allowing attackers to inject arbitrary HTTP headers and response body content. This can lead to malicious JavaScript execution in a victim's browser.

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Detection Guidance

To detect CVE-2026-39915, monitor HTTP responses for unsanitized CRLF sequences in the rt URL parameter or access_token cookie. Check if these values appear in Set-Cookie headers. Use tools like curl to inspect responses for injected headers or JavaScript payloads. Example: curl -v 'http://target.com/path?rt=value%0d%0aSet-Cookie:malicious=1'

Inspect web server logs for unusual requests containing %0d%0a (URL-encoded CRLF) or raw CRLF characters. Automated scanners like Burp Suite or OWASP ZAP can also detect this vulnerability by analyzing header injection patterns.

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Impact Analysis

An attacker could trick you into clicking a malicious link, causing your browser to execute arbitrary JavaScript. This could steal your session tokens, modify account credentials, or perform actions on your behalf without your knowledge.

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Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, violating GDPR's data protection principles and HIPAA's security requirements. It may result in data breaches, unauthorized disclosure, or modification of protected health information.

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Mitigation Strategies

Upgrade TIM Flow to version 26.0.6 or later immediately. If upgrading is not possible, implement input validation to sanitize the rt parameter and access_token cookie, removing CRLF sequences before processing. Configure web application firewalls to block requests containing %0d%0a or raw CRLF characters.

Apply strict output encoding to prevent reflection of unsanitized inputs in HTTP headers. Monitor for suspicious activity, such as unexpected Set-Cookie headers or JavaScript execution in user sessions.

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