CVE-2026-103863
Received Received - Intake

Stored XSS in Apache Sling Engine

Publication date: 2026-11-05

Last updated on: 2026-11-05

Assigner: Apache Software Foundation

Description
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.

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Meta Information

Published
2026-11-05
Last Modified
2026-11-05
Generated
2026-11-05
AI Q&A
2026-11-05
EPSS Evaluated
N/A
NVD
CVE-2026-103863
EUVD
EUVD-2026-117431

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
Apache Software Foundation Apache Sling Engine 0

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-79 The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.
CWE-693 The product does not use or incorrectly uses a protection mechanism that provides sufficient defense against directed attacks against the product.

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Executive Summary

This is a cross-site scripting (XSS) vulnerability in Apache Sling Engine before version 3.0.4. It occurs due to improper neutralization of input during web page generation, allowing attackers to bypass protections like protectheaders and checkcontenttype. The issue stems from setHeader(), repeated setContentType() calls, charset APIs, Servlet 6.1 redirect overloads, and stale configurations.

Impact Analysis

An attacker could exploit this to inject malicious scripts into web pages served by Apache Sling Engine. This could lead to theft of user sessions, credentials, or sensitive data, defacement of websites, or redirection to malicious sites. Users of affected versions are at risk until they upgrade.

Compliance Impact

This XSS vulnerability could lead to unauthorized access to user data, violating GDPR's data protection principles and HIPAA's security requirements for protected health information. Organizations may face compliance violations, legal penalties, and reputational damage if exploited.

Mitigation Strategies

Upgrade Apache Sling Engine to version 3.0.4 or later to address the XSS vulnerability caused by improper header and content type handling.

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