CVE-2025-4945 identifies an integer overflow vulnerability in the cookie parsing logic of the libsoup HTTP library, which is widely used in GNOME applications and other software stacks, including Red Hat Enterprise Linux 10. The vulnerability arises during the processing of cookie expiration dates, where the library performs date arithmetic without properly validating large integer inputs. An attacker can craft a cookie with a specially designed expiration date value that triggers an integer overflow or wraparound. This overflow leads to undefined behavior in the cookie expiration logic, effectively bypassing the intended expiration checks. As a result, cookies that should have expired may be treated as valid, enabling persistent or unintended cookie behavior. This can be exploited to maintain unauthorized sessions or manipulate authentication states relying on cookies. The vulnerability does not directly compromise confidentiality or availability but impacts the integrity of session management. Exploitation requires no privileges or user interaction, but the attack surface is limited to applications using the vulnerable libsoup library for HTTP cookie handling. No known exploits have been reported in the wild, and the CVSS v3.1 base score is 3.7, reflecting a low severity due to the limited impact and complexity of exploitation. The root cause is improper input validation and arithmetic handling within the cookie parsing routines, highlighting the need for robust input sanitization and boundary checks in security-critical libraries.

For European organizations, the primary impact of CVE-2025-4945 lies in the potential for attackers to bypass cookie expiration mechanisms, leading to persistent session cookies or unauthorized session continuation. This can undermine session management integrity, potentially allowing attackers to maintain access beyond intended timeframes or circumvent logout mechanisms. While the vulnerability does not directly expose sensitive data or disrupt service availability, it can facilitate longer-term unauthorized access, increasing the risk of further exploitation or lateral movement within networks. Organizations relying on GNOME applications or Red Hat Enterprise Linux 10 systems that utilize libsoup for HTTP communications are most at risk. This includes sectors with high reliance on Linux desktop environments or server applications using these libraries. The low CVSS score and absence of known exploits suggest a limited immediate threat, but the persistence of session cookies can complicate incident response and user session control. European entities with strict compliance requirements around session management and data protection may face regulatory scrutiny if such vulnerabilities are exploited. Therefore, timely patching and monitoring are essential to maintain secure session handling and prevent potential abuse.

To mitigate CVE-2025-4945, European organizations should prioritize updating the libsoup library to the patched version provided by Red Hat or their respective Linux distribution vendors as soon as it becomes available. In the interim, organizations can implement strict cookie management policies, including limiting cookie lifetimes and enforcing server-side session expiration controls independent of client-side cookie expiration. Application developers should review and harden cookie parsing and validation logic to reject suspicious or malformed expiration date values. Network security teams can monitor HTTP traffic for anomalous cookie expiration headers or unusual session persistence patterns that may indicate exploitation attempts. Employing web application firewalls (WAFs) with custom rules to detect and block malformed cookies can provide additional protection. Regular security audits and penetration testing focusing on session management and cookie handling will help identify residual risks. Finally, educating users and administrators about the importance of applying security updates promptly and maintaining secure session practices will reduce the window of exposure.