CVE-2025-4945 in libsoup
Summary
by MITRE • 05/19/2025
A flaw was found in the cookie parsing logic of the libsoup HTTP library, used in GNOME applications and other software. The vulnerability arises when processing the expiration date of cookies, where a specially crafted value can trigger an integer overflow. This may result in undefined behavior, allowing an attacker to bypass cookie expiration logic, causing persistent or unintended cookie behavior. The issue stems from improper validation of large integer inputs during date arithmetic operations within the cookie parsing routines.
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Analysis
by VulDB Data Team • 01/07/2026
The vulnerability identified as CVE-2025-4945 resides within the libsoup HTTP library, a critical component that serves as the foundation for HTTP communication in numerous GNOME applications and broader software ecosystems. This library handles cookie management as part of its core functionality, making it a prime target for attackers seeking to manipulate session state and authentication mechanisms. The flaw manifests specifically in the cookie parsing logic where the library processes expiration dates, creating a pathway for malicious actors to exploit the underlying implementation through carefully crafted cookie values. The issue represents a fundamental breakdown in input validation and processing that affects the integrity of session management across applications relying on this library.
The technical root cause of CVE-2025-4945 stems from an integer overflow condition that occurs during the processing of cookie expiration dates. When the library encounters a specially crafted cookie value containing an excessively large integer representing the expiration timestamp, the arithmetic operations involved in date parsing fail to properly validate the input boundaries. This overflow condition leads to unpredictable behavior where the cookie expiration logic becomes compromised, allowing attackers to manipulate the timing and validity of session cookies. The vulnerability falls under CWE-190, which specifically addresses integer overflow conditions, and more broadly aligns with CWE-191, covering integer underflow scenarios that can result in similar exploitable behaviors. The improper validation of large integer inputs during date arithmetic operations creates a direct pathway for attackers to bypass intended security controls.
The operational impact of this vulnerability extends beyond simple session manipulation to potentially enable persistent unauthorized access and stateful attacks against affected applications. When cookie expiration logic is bypassed, attackers can maintain access to systems and resources long after intended session timeouts should have occurred, effectively extending their operational window. This behavior can lead to extended privilege escalation opportunities, data exfiltration, and unauthorized administrative access to applications that depend on libsoup for their HTTP functionality. The vulnerability affects not only individual applications but creates a systemic risk across the entire GNOME ecosystem and any software projects that incorporate this library, potentially compromising thousands of end-user systems and enterprise applications simultaneously. The undefined behavior resulting from the integer overflow can also cause application instability and crashes, creating additional attack vectors through denial of service conditions.
Mitigation strategies for CVE-2025-4945 must address both immediate remediation and long-term architectural improvements to prevent similar vulnerabilities from emerging. Organizations should prioritize updating to patched versions of libsoup and any affected applications that rely on this library, ensuring that all dependencies are current with security patches. System administrators should implement monitoring for unusual cookie behavior and implement additional validation layers at network boundaries to detect and block malformed cookie values. The vulnerability highlights the importance of robust input validation and proper integer handling in security-critical code, aligning with ATT&CK technique T1555.004 for credential access through session management manipulation. Additionally, developers should adopt defensive programming practices including explicit bounds checking, overflow detection mechanisms, and comprehensive testing of edge cases involving large integer inputs to prevent similar issues in future implementations.