The Geo Mashup plugin for WordPress suffers from a stored cross-site scripting vulnerability due to improper neutralization of input during web page generation (CWE-79). Specifically, the geo_mashup_visible_posts_list shortcode does not adequately sanitize or escape user-supplied attributes, allowing authenticated attackers with contributor-level privileges or higher to inject arbitrary JavaScript code. This malicious code executes in the context of any user who accesses the compromised page, potentially leading to session hijacking or other client-side attacks. The vulnerability affects all versions up to and including 1.13.13. The CVSS 3.1 vector is AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N, reflecting network attack vector, low attack complexity, required privileges, no user interaction, scope change, and low impact on confidentiality and integrity, with no impact on availability.

An attacker with contributor-level or higher access can inject persistent malicious scripts into pages via the vulnerable shortcode. These scripts execute in the browsers of users who view the infected pages, potentially compromising user sessions or performing unauthorized actions within the affected site context. The impact is limited to confidentiality and integrity with no direct availability impact. There are no known active exploits reported.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is released, restrict contributor-level access to trusted users only and consider disabling or removing the Geo Mashup plugin if feasible. Monitor for updates from the vendor or plugin author regarding patches or official mitigations.