Textpattern CMS version 4.9.0 contains a second-order cross-site scripting vulnerability that allows attackers to inject malicious scripts by exploiting improper sanitization of user-supplied input in Atom feed XML elements. Attackers can embed unescaped payloads in parameters such as category that are reflected into Atom fields like and , which execute as JavaScript when feed readers or CMS aggregators consume the feed and insert content into the DOM using unsafe methods.
Published: 2026-03-20
Updated: 2026-03-24
Base Score: 6.4
Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:N
Severity: Medium
Base Score: 6.1
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Severity: Medium
Base Score: 5.1
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
Severity: Medium
EPSS: 0.00029