CVE-2026-0668 in VisualData Extension
Summary
by MITRE • 01/07/2026
Inefficient Regular Expression Complexity vulnerability in Wikimedia Foundation MediaWiki - VisualData Extension allows Regular Expression Exponential Blowup.This issue affects MediaWiki - VisualData Extension: 1.45.
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Analysis
by VulDB Data Team • 02/26/2026
The inefficient regular expression complexity vulnerability in the Wikimedia Foundation MediaWiki VisualData Extension represents a critical security flaw that enables regular expression exponential blowup attacks. This vulnerability specifically impacts version 1.45 of the VisualData extension, which is part of the broader MediaWiki platform used extensively across Wikimedia projects including Wikipedia. The flaw arises from the extension's improper handling of regular expressions during data processing operations, creating a condition where maliciously crafted input can trigger catastrophic performance degradation through exponential time complexity behavior.
The technical implementation of this vulnerability stems from the extension's use of regular expressions that are susceptible to backtracking attacks, a well-documented class of vulnerabilities that fall under CWE-1321. When processing user-supplied data containing carefully constructed patterns, the regular expression engine undergoes exponential time complexity growth, potentially leading to denial of service conditions where system resources become exhausted. This behavior directly aligns with ATT&CK technique T1496 which describes resource exhaustion attacks that can be achieved through inefficient algorithmic implementations. The vulnerability manifests when the extension processes input data that contains regular expression patterns designed to cause the engine to explore an exponential number of possible matching paths.
The operational impact of this vulnerability extends beyond simple performance degradation to potentially enable complete system unavailability. An attacker can craft malicious input that causes the regular expression engine to consume excessive CPU cycles and memory resources, effectively creating a denial of service condition that affects legitimate users. This vulnerability is particularly concerning in the context of MediaWiki's widespread use where the VisualData extension might process data from multiple contributors, making it a prime target for exploitation. The exponential blowup behavior means that even relatively small malicious inputs can cause disproportionate system resource consumption, making detection and mitigation challenging.
Mitigation strategies for this vulnerability should focus on implementing proper input validation and sanitization techniques to prevent malicious regular expression patterns from reaching the vulnerable code paths. The extension should be updated to use more efficient regular expression patterns that avoid backtracking issues, and input data should be validated against known malicious patterns before processing. Additionally, implementing timeouts and resource limits for regular expression operations can help prevent complete system exhaustion. Organizations should also consider implementing monitoring and alerting systems to detect unusual resource consumption patterns that might indicate exploitation attempts. The fix should align with security best practices outlined in OWASP Top Ten and should be validated through comprehensive testing to ensure that legitimate functionality remains intact while eliminating the vulnerability path.