CVE-2026-91999: Apache Sling Xss Protection API

Medium severity, CVSS 6.1. EPSS: 0.4% chance of exploitation in the next 30 days.

Improper neutralization of input during web page generation ('cross-site scripting') vulnerability in Apache Sling XSS. This issue affects Apache Sling XSS: before 2.4.12. Users are recommended to upgrade to version 2.4.12, which fixes the issue.

Affected products

• Apache Sling Xss Protection API: before 2.4.12 (fixed in 2.4.12)

Published 2026-09-23. Last modified 2026-09-30.