CVE-2025-46528 is a Cross-Site Request Forgery (CSRF) vulnerability identified in the Steve Availability Calendar product, affecting versions up to and including 0.2.4. The vulnerability allows an attacker to perform unauthorized actions on behalf of an authenticated user without their consent. Specifically, this CSRF flaw enables Stored Cross-Site Scripting (XSS) attacks, where malicious scripts injected by an attacker are permanently stored on the target system and executed in the context of legitimate users' browsers. The combination of CSRF and Stored XSS significantly elevates the risk, as attackers can trick authenticated users into submitting crafted requests that result in persistent malicious code being stored and executed. This can lead to session hijacking, credential theft, unauthorized actions, or further exploitation of the affected system. The vulnerability arises due to inadequate validation of user requests and insufficient anti-CSRF protections in the Availability Calendar application. No patches or fixes have been published yet, and there are no known exploits in the wild at this time. The vulnerability was publicly disclosed on April 24, 2025, and is tracked under CWE-352, which highlights weaknesses in CSRF protections.

For European organizations, the impact of this vulnerability can be significant, especially for those relying on the Steve Availability Calendar for scheduling and resource management. Exploitation could lead to unauthorized changes in calendar data, leakage of sensitive scheduling information, and compromise of user accounts through Stored XSS attacks. This can disrupt business operations, damage organizational reputation, and potentially expose confidential information. Organizations in sectors such as finance, healthcare, government, and critical infrastructure, where scheduling tools are integrated into broader IT ecosystems, may face increased risks of lateral movement and data breaches. The persistent nature of Stored XSS also raises concerns about long-term compromise and the difficulty of detection. Although no active exploitation has been reported, the medium severity rating suggests that attackers with moderate skills could exploit this vulnerability, especially if users are authenticated and targeted via social engineering or phishing campaigns.

To mitigate this vulnerability, European organizations should implement the following specific measures: 1) Immediately review and restrict access to the Steve Availability Calendar, limiting it to trusted users and networks until a patch is available. 2) Employ web application firewalls (WAFs) with custom rules to detect and block suspicious CSRF and XSS payloads targeting the calendar application. 3) Enforce strict Content Security Policy (CSP) headers to reduce the impact of Stored XSS by restricting script execution sources. 4) Educate users about phishing and social engineering tactics that could be used to trigger CSRF attacks, emphasizing caution when clicking on unsolicited links while authenticated. 5) Monitor application logs and user activity for unusual requests or modifications indicative of CSRF exploitation attempts. 6) Engage with the vendor or community to obtain patches or updates as soon as they become available, and plan for timely deployment. 7) Consider implementing multi-factor authentication (MFA) for access to the calendar system to reduce the risk of session hijacking. 8) Conduct regular security assessments and penetration testing focused on CSRF and XSS vectors within the affected application environment.