Source: cve@mitre.org
Cross-site scripting (XSS) vulnerability in the default markup formatter in Jenkins 1.523 allows remote attackers to inject arbitrary web script or HTML via the Description field in the user configuration.
Jenkins, a popular open-source automation server, is vulnerable to a cross-site scripting (XSS) attack. This allows attackers to inject malicious HTML or JavaScript into the application, potentially leading to session hijacking, data theft, or complete control of the user's browser and potentially the Jenkins server itself.
The vulnerability stems from insufficient input validation and output encoding within Jenkins' default markup formatter when processing the 'Description' field in user configurations. Specifically, the application fails to properly sanitize user-supplied input before rendering it in the web interface. This allows an attacker to inject malicious JavaScript or HTML tags into the description field. When a user views the user configuration, the injected script executes within the context of their browser, enabling the attacker to perform actions on their behalf.
While no specific APT groups are definitively linked to this specific CVE, the ease of exploitation and the potential impact make it attractive to various threat actors. This vulnerability is not listed on the CISA KEV at the time of this report.
Monitor HTTP requests for unusual patterns in the 'Description' field of user configurations, specifically looking for HTML tags or JavaScript code.
Analyze server-side logs for suspicious activity related to user configuration changes, focusing on the time of the change and the content of the description field.
Implement a web application firewall (WAF) to filter out malicious payloads in HTTP requests.
Use a content security policy (CSP) to restrict the sources from which the browser can load resources, mitigating the impact of XSS attacks.
Upgrade Jenkins to a patched version that addresses the XSS vulnerability. The specific patch is included in Jenkins 1.524 and later.
Implement a robust input validation and output encoding strategy to sanitize user-supplied data before rendering it in the web interface.
Use a Content Security Policy (CSP) to restrict the execution of inline scripts and the loading of external scripts from untrusted sources.
Regularly scan Jenkins instances for vulnerabilities and apply security patches promptly.
Educate users about the risks of clicking on suspicious links or opening attachments from untrusted sources.