CVE-2025-61689 is a vulnerability classified under CWE-113, involving improper neutralization of CRLF (Carriage Return Line Feed) sequences in HTTP headers within the HTTP.jl library used by the Julia programming language. HTTP.jl provides HTTP client and server functionalities, and prior to version 1.10.19, it failed to validate header names and values for illegal characters, specifically CRLF sequences. This oversight allows attackers to inject malicious CRLF sequences into HTTP headers, leading to HTTP response splitting and header injection attacks. Such attacks enable an adversary to manipulate HTTP responses, potentially causing cache poisoning, cross-site scripting (XSS), session fixation, and other web security issues. The vulnerability is exploitable remotely over the network without requiring authentication or user interaction, increasing its risk profile. The CVSS 4.0 base score of 8.7 reflects the high impact on confidentiality and integrity, with a low attack complexity and no privileges required. Although no known exploits are currently reported in the wild, the vulnerability's nature and impact necessitate prompt remediation. The issue was addressed in HTTP.jl version 1.10.19 by implementing proper validation and sanitization of HTTP header fields to prevent CRLF injection. Organizations using HTTP.jl in their Julia-based web services or applications must upgrade to this patched version to mitigate the risk. Additionally, developers should audit their code for any custom header handling that might be vulnerable to similar injection attacks.

For European organizations, the impact of CVE-2025-61689 can be significant, especially for those relying on Julia and HTTP.jl in web-facing applications or internal services. Exploitation could lead to cache poisoning, which undermines data integrity and can serve malicious content to users. XSS attacks facilitated by this vulnerability can compromise user sessions, steal sensitive data, or perform unauthorized actions on behalf of users, affecting confidentiality and trust. Session fixation attacks may allow attackers to hijack user sessions, leading to unauthorized access. The vulnerability's network-level exploitability without authentication means attackers can target vulnerable systems remotely, increasing the attack surface. This is particularly critical for sectors such as finance, research, and technology, where Julia is popular and where data confidentiality and integrity are paramount. The potential for widespread impact is heightened in environments where HTTP.jl is used as a core component of web infrastructure without additional mitigations. Failure to address this vulnerability could result in regulatory non-compliance under GDPR if personal data is compromised, leading to legal and financial repercussions.

European organizations should immediately upgrade HTTP.jl to version 1.10.19 or later to remediate the vulnerability. Beyond patching, developers must implement strict validation and sanitization of all HTTP header inputs, ensuring that CRLF sequences and other control characters are properly neutralized before processing or forwarding headers. Conduct thorough code reviews and security testing focused on header injection vectors, especially in custom HTTP handling code. Employ web application firewalls (WAFs) with rules designed to detect and block HTTP response splitting and header injection attempts. Monitor web server and application logs for unusual header patterns or anomalies indicative of exploitation attempts. Educate development teams on secure HTTP header practices and the risks of improper input validation. For critical systems, consider deploying runtime application self-protection (RASP) solutions to detect and mitigate injection attacks in real-time. Finally, maintain an inventory of all systems using HTTP.jl to ensure comprehensive patch management and vulnerability tracking.