CVE-2024-25111 is a vulnerability classified under CWE-674 (Uncontrolled Recursion) affecting the Squid web proxy cache software versions starting from 3.5.27 up to but excluding 6.8. The flaw resides in the HTTP Chunked decoder component, where improper handling of chunked-encoded HTTP messages leads to uncontrolled recursion. This recursion can be triggered remotely by an attacker sending a crafted chunked HTTP request, causing the Squid process to consume excessive stack or memory resources, ultimately resulting in a Denial of Service (DoS) condition. The vulnerability requires no authentication or user interaction, making it remotely exploitable over the network. The impact is limited to availability, as the attacker cannot compromise confidentiality or integrity of data. The issue was publicly disclosed on March 6, 2024, with a CVSS v3.1 base score of 8.6, indicating high severity. The fix is included in Squid version 6.8, and patches for stable releases are available in Squid's patch archives. No known exploits are currently reported in the wild. Due to the lack of a workaround, affected organizations must apply patches promptly to mitigate risk. Squid is widely used in enterprise and ISP environments for caching and proxying HTTP traffic, making this vulnerability relevant to many network infrastructures.

For European organizations, the primary impact of CVE-2024-25111 is the potential disruption of web proxy services that rely on Squid. This can lead to degraded network performance, loss of caching benefits, and interruption of HTTP traffic filtering or access controls, affecting business continuity and user productivity. Organizations using Squid as part of their security stack or content delivery infrastructure may experience outages or degraded service availability. Critical sectors such as telecommunications, financial services, government agencies, and large enterprises that depend on Squid proxies for traffic management are particularly at risk. The vulnerability does not expose sensitive data or allow code execution, but the resulting DoS can be leveraged as part of a broader attack strategy to disrupt operations. The absence of known exploits reduces immediate risk but does not eliminate the threat, especially given the ease of exploitation and public disclosure. Failure to patch may also increase exposure to automated scanning and exploitation attempts in the near future.

European organizations should prioritize upgrading Squid installations to version 6.8 or later, where the vulnerability is fully resolved. For environments unable to upgrade immediately, applying the official patches available in Squid's patch archives for stable releases is essential. Network administrators should implement monitoring and alerting for anomalous HTTP chunked transfer-encoded traffic patterns that may indicate exploitation attempts. Deploying rate limiting or filtering on HTTP chunked requests at perimeter devices can reduce exposure. Additionally, organizations should review proxy usage policies to limit exposure to untrusted sources and segment proxy servers to contain potential DoS impacts. Regular vulnerability scanning and asset inventory updates will help identify all affected Squid instances. Incident response plans should be updated to address potential DoS scenarios involving proxy infrastructure. Finally, maintaining up-to-date backups and redundancy for critical proxy services will aid in rapid recovery if disruption occurs.