CVE-2025-46420 identifies a memory leak vulnerability in the libsoup library, specifically within the soup_header_parse_quality_list() function. Libsoup is a widely used HTTP client/server library in Linux environments, including Red Hat Enterprise Linux 8. The vulnerability arises when the function parses a quality list header containing elements with all zeroes, failing to release allocated memory after the effective lifetime of these elements. This results in a gradual increase in memory consumption, which can degrade system performance and eventually cause denial of service due to resource exhaustion. The vulnerability has a CVSS 3.1 base score of 6.5, indicating a medium severity level. The attack vector is network-based (AV:N), with low attack complexity (AC:L), no privileges required (PR:N), but requires user interaction (UI:R). The impact affects availability (A:H) but not confidentiality or integrity. No known exploits have been reported in the wild to date. The flaw affects Red Hat Enterprise Linux 8, a common enterprise Linux distribution, which means many servers and applications could be impacted if they use libsoup for HTTP communications. The vulnerability is particularly relevant for services parsing HTTP headers that include quality lists, such as content negotiation headers. Since the issue is a memory leak, it may be exploited by sending specially crafted HTTP requests repeatedly to exhaust server memory over time. This could lead to service crashes or degraded performance, impacting availability of critical services.

For European organizations, this vulnerability poses a risk primarily to availability of services running on Red Hat Enterprise Linux 8 that utilize libsoup. Memory leaks can cause gradual degradation of system performance, potentially leading to denial of service conditions. This is especially critical for public-facing web services, APIs, and internal applications relying on HTTP communications via libsoup. Organizations in sectors such as finance, healthcare, government, and critical infrastructure could experience service interruptions, impacting business continuity and operational resilience. The lack of confidentiality or integrity impact reduces the risk of data breaches, but availability issues can still cause significant operational disruption. Since exploitation requires user interaction, the risk is somewhat mitigated but still relevant in environments with exposed network services. The absence of known exploits in the wild suggests limited immediate threat, but proactive mitigation is advised to prevent future exploitation attempts.

1. Monitor official Red Hat security advisories and apply patches for libsoup and Red Hat Enterprise Linux 8 as soon as they become available. 2. Implement network-level protections such as web application firewalls (WAFs) to detect and block suspicious HTTP requests containing malformed or zeroed quality lists. 3. Employ resource monitoring tools to track memory usage trends on servers running libsoup, enabling early detection of abnormal memory consumption. 4. Limit exposure of services using libsoup to trusted networks or VPNs to reduce attack surface. 5. Conduct regular security assessments and penetration testing focusing on HTTP header parsing and related components. 6. Educate users and administrators about the potential for denial of service via crafted HTTP requests and encourage reporting of unusual service behavior. 7. Consider temporary workarounds such as rate limiting or filtering HTTP headers with suspicious quality list elements until patches are applied.