CVE-2026-4859 is a stored cross-site scripting vulnerability in the SP Blog Designer WordPress plugin (versions up to 1.0.0). It occurs due to improper neutralization of input in the 'design' attribute of the wpsbd_post_carousel shortcode, allowing authenticated users with Contributor or higher privileges to inject arbitrary web scripts. These scripts execute in the context of any user viewing the injected page, potentially leading to session hijacking or other script-based attacks. The vulnerability has a CVSS 3.1 base score of 6.4 (AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N), reflecting network attack vector, low attack complexity, and partial impact on confidentiality and integrity with no impact on availability. No vendor patch or official remediation is currently documented.

An attacker with Contributor-level or higher access can inject persistent malicious scripts into pages via the vulnerable shortcode attribute. These scripts execute in the browsers of users viewing the affected pages, potentially compromising user sessions or data confidentiality and integrity. The vulnerability does not affect availability. There are no known active exploits reported.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, limit Contributor-level access to trusted users only and consider removing or disabling the SP Blog Designer plugin if feasible. Monitor official vendor channels for updates or patches addressing this vulnerability.