CVE-2020-2257: 
Java vulnerability analysis and mitigation

CVE-2020-2257 is a stored cross-site scripting (XSS) vulnerability affecting the Jenkins Validating String Parameter Plugin versions 2.4 and earlier. The vulnerability was discovered and disclosed on September 16, 2020. The issue affects the plugin's handling of regular expressions in tooltips, parameter names, and parameter descriptions (Jenkins Advisory).

The vulnerability is classified as a stored XSS vulnerability with a High severity CVSS rating. The issue occurs because the Validating String Parameter Plugin 2.4 and earlier versions fail to properly escape regular expressions in tooltips, parameter names, and parameter descriptions. This security flaw is tracked as SECURITY-1935 in Jenkins security tracking system (Jenkins Advisory).

The vulnerability allows attackers with Job/Configure permission to execute cross-site scripting (XSS) attacks through the manipulation of regular expressions in tooltips, parameter names, and parameter descriptions (Jenkins Advisory).

The vulnerability is exploitable by attackers who have Job/Configure permission in the Jenkins environment. The attacker can inject malicious scripts through the plugin's parameter configuration interface (Jenkins Advisory).

The vulnerability has been fixed in Validating String Parameter Plugin version 2.5. The fix includes proper escaping of regular expressions in tooltips and parameter names, while parameter descriptions are now rendered using the configured markup formatter. Users are advised to upgrade to version 2.5 or later to address this security issue (Jenkins Advisory).