Bug 2567481 (CVE-2026-103863)

Summary: CVE-2026-103863 org.apache.sling/org.apache.sling.engine: Apache Sling Engine: Stored Cross-Site Scripting via header protection bypass
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Apache Sling Engine. This vulnerability allows an attacker to conduct stored Cross-Site Scripting (XSS) attacks by evading security header protections. Included components can bypass header and content-type enforcement mechanisms through manipulated response headers, character set configurations, or redirect calls, enabling malicious scripts to be stored and executed within a user's browser session.
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Description OSIDB Bzimport 2026-11-05 22:01:23 UTC
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.