CVE-2025-46420 is a vulnerability identified in the libsoup library, specifically within the soup_header_parse_quality_list() function. This function is responsible for parsing HTTP header quality lists, which are used to indicate preferences for content negotiation in HTTP requests and responses. The flaw arises when the function processes a quality list containing elements with all zero values, leading to a failure to release allocated memory after its effective lifetime. This results in a memory leak, where memory that is no longer needed is not freed, causing the application to consume increasing amounts of memory over time. The vulnerability affects Red Hat Enterprise Linux 8, as libsoup is commonly used in GNOME and other Linux desktop and server environments for HTTP client functionality. The CVSS 3.1 base score is 6.5, indicating a medium severity level. The vector indicates that the attack can be performed remotely (AV:N), with low attack complexity (AC:L), no privileges required (PR:N), but requires user interaction (UI:R). The impact is limited to availability (A:H), meaning the memory leak could degrade system performance or cause denial of service due to resource exhaustion, but does not affect confidentiality or integrity. No known exploits are currently in the wild, and no patches have been linked yet. The vulnerability does not require authentication but does require the victim to interact with crafted HTTP headers containing the problematic quality list. This flaw could be exploited by an attacker sending specially crafted HTTP requests to applications or services using libsoup for HTTP parsing, potentially leading to service degradation or crashes over time due to memory exhaustion.

For European organizations, the primary impact of CVE-2025-46420 is on the availability of systems running Red Hat Enterprise Linux 8 that utilize libsoup for HTTP communications. Memory leaks can lead to gradual resource depletion, causing applications or services to slow down, become unresponsive, or crash, resulting in denial of service conditions. This can disrupt business operations, especially for web services, APIs, or internal tools relying on libsoup. While the vulnerability does not compromise data confidentiality or integrity, the availability impact can affect critical infrastructure, customer-facing services, or internal workflows. Organizations with high uptime requirements or those operating in sectors such as finance, healthcare, or public services may experience operational risks. Additionally, since exploitation requires user interaction, phishing or social engineering campaigns could be used to trick users into triggering the vulnerability via crafted HTTP responses or intermediaries. The absence of known exploits in the wild suggests limited immediate risk, but the medium severity and ease of remote exploitation warrant proactive mitigation.

To mitigate CVE-2025-46420, European organizations should: 1) Monitor for and apply security updates from Red Hat as soon as patches become available for libsoup or related packages in Red Hat Enterprise Linux 8. 2) Implement network-level filtering to detect and block suspicious HTTP headers or traffic patterns that include malformed or suspicious quality lists, potentially using web application firewalls (WAFs) or intrusion detection systems (IDS). 3) Limit exposure of services using libsoup to untrusted networks or users, employing segmentation and access controls to reduce attack surface. 4) Educate users and administrators about the risk of interacting with untrusted HTTP content, especially in environments where user interaction triggers the vulnerability. 5) Employ resource monitoring and alerting to detect abnormal memory usage or application crashes that could indicate exploitation attempts. 6) Consider deploying application-layer proxies or HTTP sanitization tools that can normalize or reject malformed headers before they reach vulnerable libsoup instances. 7) Review and harden configurations of services using libsoup to minimize unnecessary HTTP header processing or to disable features that parse quality lists if not required.