CVE-2025-11175 is a vulnerability classified under CWE-917, which pertains to improper neutralization of special elements used in expression language statements. Specifically, it affects the DiscussionTools Extension of Mediawiki versions 1.43 and 1.44. The vulnerability arises because the extension fails to properly sanitize or neutralize special characters or expressions within its expression language processing, allowing an attacker to craft malicious input that triggers a Regular Expression Exponential Blowup (ReDoS). This type of attack exploits the way regular expressions are evaluated, causing the system to consume excessive CPU and memory resources, leading to denial of service. The vulnerability is remotely exploitable without requiring authentication or user interaction, increasing its risk profile. The CVSS 4.0 vector indicates network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), high impact on confidentiality (VC:H), low impact on integrity (VI:L), no impact on availability (VA:N), low scope change (SC:L), low impact on integrity scope (SI:L), and no impact on availability scope (SA:N). However, the description of ReDoS implies a significant availability impact through resource exhaustion, which may not be fully captured in the vector. No patches are currently linked, and no known exploits have been reported in the wild, but the vulnerability is publicly disclosed and should be addressed promptly. The root cause is insufficient input validation and improper handling of expression language elements in the DiscussionTools Extension, which is used to enhance discussion features in Mediawiki platforms. Exploitation could disrupt wiki services, degrade performance, and potentially allow partial data integrity issues due to malformed inputs.

For European organizations, the primary impact of CVE-2025-11175 is the potential for denial of service attacks against Mediawiki instances using the DiscussionTools Extension versions 1.43 or 1.44. This can lead to service outages, disrupting collaboration, knowledge sharing, and documentation workflows critical to business and government operations. The vulnerability could also be leveraged to degrade system performance, increasing operational costs and reducing user trust. While confidentiality impact is rated high in the CVSS vector, the actual risk to data confidentiality is limited; however, partial integrity issues could arise from malformed inputs affecting discussion content. Organizations relying on Mediawiki for internal or public-facing knowledge bases, especially those in sectors such as government, education, and critical infrastructure, may face operational risks. The lack of authentication or user interaction requirements means attackers can exploit this remotely and anonymously, increasing the threat surface. Additionally, the absence of known exploits currently does not preclude future weaponization, so proactive mitigation is essential to avoid potential widespread disruption across European entities.

1. Immediately upgrade the DiscussionTools Extension to a patched version once available from The Wikimedia Foundation. Monitor official channels for patch releases. 2. Until patches are available, implement web application firewall (WAF) rules to detect and block suspicious payloads targeting expression language inputs, especially those containing complex or nested regular expressions. 3. Apply input validation and sanitization at the application layer to neutralize special characters or expressions before processing. 4. Limit resource consumption for regular expression evaluation by setting timeouts or maximum processing limits in the application or underlying runtime environment. 5. Monitor logs for anomalous spikes in CPU or memory usage related to Mediawiki services, and set alerts for potential ReDoS attack patterns. 6. Restrict network access to Mediawiki instances to trusted users or IP ranges where feasible, reducing exposure to remote attacks. 7. Conduct security reviews of custom Mediawiki extensions or configurations to identify similar expression language injection risks. 8. Educate development and operations teams about the risks of expression language injection and secure coding practices to prevent recurrence. 9. Maintain an incident response plan to quickly isolate and remediate affected systems in case of exploitation.