Optimole < 4.2.12 - Unauthenticated Stored XSS via Srcset Descriptor Parameter

Description

The plugin does not properly escape a user supplied value before using it to build an image tag attribute, allowing unauthenticated users to inject arbitrary attributes into pages served to every visitor, which leads to Stored Cross-Site Scripting.
The escaping added in 4.2.3 for CVE-2026-5217 does not cover the context the value is finally used in, so releases from 4.2.3 onwards remain affected.