CVE-2022-42985 is a medium-severity vulnerability affecting the ScratchLogin extension for MediaWiki, specifically versions up to 1.1. The vulnerability arises because the extension fails to properly escape verification failure messages. This improper handling allows users with administrator privileges to inject malicious scripts via cross-site scripting (XSS) attacks. The vulnerability is categorized under CWE-79, which relates to improper neutralization of input during web page generation, leading to XSS. In this case, the attack vector requires an authenticated administrator user to trigger the vulnerability by causing the extension to display crafted verification failure messages that include malicious JavaScript code. Since the flaw is in the message escaping mechanism, the injected script can execute in the context of the administrator's browser session, potentially allowing session hijacking, privilege escalation, or unauthorized actions within the MediaWiki environment. There are no known exploits in the wild as of the published date (November 17, 2022), and no patches or vendor advisories have been linked. The vulnerability is specific to the ScratchLogin extension, which is an add-on to MediaWiki, a widely used open-source wiki platform. The lack of a CVSS score means severity must be assessed based on impact and exploitability factors.

For European organizations using MediaWiki with the ScratchLogin extension, this vulnerability poses a risk primarily to the confidentiality and integrity of the wiki content and administrative sessions. Since exploitation requires administrator privileges, the attack surface is limited to trusted users, but successful exploitation could allow an attacker to execute arbitrary scripts in the admin's browser, potentially leading to session hijacking, unauthorized changes to wiki content, or further lateral movement within the organization's network. This could compromise sensitive documentation, internal knowledge bases, or collaborative projects hosted on MediaWiki. The impact on availability is limited, as the vulnerability does not directly cause denial of service. However, the reputational damage and operational disruption from compromised administrative accounts could be significant. European organizations in sectors relying heavily on MediaWiki for internal collaboration—such as government agencies, research institutions, and large enterprises—may face increased risk. The absence of known exploits reduces immediate threat but does not eliminate risk, especially if attackers develop targeted exploits. Additionally, the vulnerability could be leveraged in spear-phishing or social engineering campaigns targeting administrators.

1. Immediate mitigation involves restricting administrator access to trusted personnel only and monitoring administrative actions within MediaWiki. 2. Organizations should audit their MediaWiki installations to identify if the ScratchLogin extension version 1.1 or earlier is in use and disable or remove the extension if possible until a patch is available. 3. Implement Content Security Policy (CSP) headers to limit the execution of unauthorized scripts within the MediaWiki environment, reducing the impact of XSS attacks. 4. Educate administrators about the risk of executing untrusted links or messages within the wiki interface. 5. Monitor logs for unusual administrative activity or unexpected verification failure messages that could indicate exploitation attempts. 6. Engage with the MediaWiki community or extension maintainers to obtain updates or patches addressing this vulnerability. 7. Consider deploying web application firewalls (WAFs) with custom rules to detect and block suspicious payloads targeting the ScratchLogin extension. 8. Regularly update MediaWiki and all extensions to the latest versions to benefit from security fixes.