CVE-2025-54363 is a vulnerability identified in Microsoft Knack version 0.12.0, specifically within the knack.introspection module. The issue is classified under CWE-1333, which pertains to inefficient regular expression complexity leading to a Regular Expression Denial of Service (ReDoS). This vulnerability arises when the application processes specially crafted input that triggers excessive backtracking in regular expression evaluation, causing the system to consume disproportionate CPU resources and become unresponsive. The vulnerability does not require authentication or user interaction and can be exploited locally (AV:L), meaning an attacker must have local access to the system to trigger the issue. The CVSS 4.0 base score is 6.9, categorized as medium severity, reflecting a high impact on availability but limited attack vector and complexity. The flaw does not affect confidentiality or integrity, nor does it involve scope or privilege escalation. There are no known exploits in the wild, and no patches have been published at the time of this report. The vulnerability could be leveraged by an attacker with local access to cause denial of service conditions, potentially disrupting services or applications relying on the knack.introspection module in Microsoft Knack 0.12.0.

For European organizations using Microsoft Knack 0.12.0, this vulnerability poses a risk primarily to system availability. If exploited, it could lead to denial of service conditions on affected systems, impacting business continuity, especially for applications or services that depend on the knack.introspection module for introspection or reflection capabilities. While the attack requires local access, insider threats or compromised internal systems could exploit this vulnerability to degrade service performance or cause outages. This could affect sectors with critical uptime requirements such as finance, healthcare, and public services. Additionally, organizations with development or testing environments running this version may experience disruptions. The lack of confidentiality or integrity impact reduces the risk of data breaches, but availability impacts could still lead to operational and reputational damage. Given the medium severity and local attack vector, the threat is moderate but should not be ignored, especially in environments where Microsoft Knack is integrated into critical workflows.

To mitigate this vulnerability, organizations should first identify all instances of Microsoft Knack 0.12.0 in their environment, focusing on systems where the knack.introspection module is utilized. Since no official patches are available, organizations should consider the following specific actions: 1) Restrict local access to systems running the vulnerable version to trusted personnel only, minimizing the risk of local exploitation. 2) Implement application-layer input validation and sanitization to detect and block maliciously crafted inputs that could trigger the ReDoS condition. 3) Monitor CPU and system resource usage on affected systems to detect abnormal spikes indicative of exploitation attempts. 4) Where feasible, isolate or sandbox applications using Microsoft Knack to limit the impact of potential denial of service. 5) Engage with Microsoft or the Knack community for updates or patches addressing this vulnerability and plan timely upgrades once fixes are available. 6) Review and enhance internal security policies to prevent unauthorized local access and improve detection of anomalous behavior related to this vulnerability.