CVE-2006-5098 in DokuWiki
Summary
by MITRE
lib/exec/fetch.php in DokuWiki before 2006-03-09e allows remote attackers to cause a denial of service (CPU consumption) via large w and h parameters, when resizing an image.
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Analysis
by VulDB Data Team • 04/23/2026
The vulnerability identified as CVE-2006-5098 resides within the DokuWiki content management system, specifically in the image processing functionality located at lib/exec/fetch.php. This flaw represents a classic denial of service attack vector that exploits improper input validation and resource handling during image manipulation operations. The vulnerability affects DokuWiki versions prior to 2006-03-09e, indicating a relatively early issue in the software's development lifecycle that was subsequently addressed by the development team.
The technical implementation of this vulnerability stems from the lack of proper parameter validation for width and height dimensions when processing image resizing requests. When attackers submit maliciously large values for the w (width) and h (height) parameters, the system attempts to process these requests without adequate bounds checking or resource limitation mechanisms. This results in the application consuming excessive cpu cycles as it attempts to resize images to impractically large dimensions, effectively creating a resource exhaustion scenario that can bring the system to its knees.
From an operational impact perspective, this vulnerability presents a significant threat to system availability and performance. The denial of service condition manifests through sustained high cpu utilization, which can affect not only the targeted image processing functionality but potentially impact the entire web application. Attackers can exploit this weakness to disrupt service availability for legitimate users, making it particularly dangerous in production environments where system uptime is critical. The vulnerability operates at the application layer and can be executed remotely without requiring authentication, making it particularly dangerous as it can be exploited by anyone with access to the affected system.
The underlying flaw aligns with CWE-400, which describes unchecked resource consumption, and represents a common pattern in web applications where input validation is insufficient to prevent malicious exploitation of resource-intensive operations. From an attack framework perspective, this vulnerability fits within the denial of service category of the MITRE ATT&CK framework, specifically targeting the availability aspect of the CIA triad. The attack vector is straightforward and can be automated, making it particularly dangerous as it requires minimal technical skill to execute effectively.
Mitigation strategies for this vulnerability include implementing proper input validation and parameter bounds checking within the image processing module. The recommended approach involves establishing maximum allowable values for width and height parameters, implementing proper resource limits, and adding appropriate error handling for out-of-bounds requests. System administrators should also ensure that all DokuWiki installations are updated to version 2006-03-09e or later, which contains the necessary patches to address this specific issue. Additionally, implementing rate limiting and monitoring mechanisms can help detect and prevent exploitation attempts, while proper logging should be enabled to track suspicious requests that attempt to consume excessive resources.