The wpopal Opal Service up to version 1.9.1 contains a stored cross-site scripting vulnerability due to improper input neutralization during web page generation. This allows attackers with low privileges to inject malicious scripts that execute in the context of other users' browsers, potentially leading to partial compromise of confidentiality, integrity, and availability. The vulnerability has a CVSS 3.1 base score of 6.5, reflecting network attack vector, low attack complexity, required privileges, and user interaction. No patch or official remediation information is currently available.

Successful exploitation of this stored XSS vulnerability can lead to limited confidentiality, integrity, and availability impacts by executing arbitrary scripts in the context of affected users. This may allow attackers to steal session tokens, manipulate page content, or perform actions on behalf of users. However, the impact is rated medium and requires user interaction and some privileges, limiting the scope of exploitation. There are no known active exploits reported at this time.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, users should apply standard XSS mitigations such as input validation and output encoding where possible. Monitor vendor channels for updates and apply patches promptly once released.