XSS in Apache Software Foundation Sling Engine
CVE-2026-103863
Improper neutralization of input during web page generation ('cross-site scripting') vulnerability in Apache Sling Engine. Content-Type, charset, and redirect changes from an included component evade the protectheaders / checkcontenttype enforcement through setHeader(), repeated calls to setContentType(), the charset APIs, Servlet 6.1 redirect overloads, and stale config - enabling stored XSS despite enabled protections. This issue affects Apache Sling Engine before 3.0.4. Users are recommended to upgrade to version 3.0.4, which fixes the issue.
Vulnerability class: XSS (Cross-Site Scripting)
Published · last modified .
EPSS exploit prediction
EPSS: 0.002 (13.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 14th percentile — 13.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
The 30-day trend appears once there are two daily scores.