Quick answers
- Is CVE-2026-103863 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-103863 being exploited in the wild.
- How severe is CVE-2026-103863?
- Informational severity, published 5 November 2026.
- Which products and versions are affected?
- Apache Sling Engine before 3.0.4.
- Is there a fix for CVE-2026-103863?
- Yes: fixed in 3.0.4. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-103863 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-103863?
- Check whether you run Apache Sling Engine at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
How to fix
- Fixed in: 3.0.4
Technical details
The vulnerability is a stored XSS in Apache Sling Engine caused by improper neutralization of input during web page generation. Included components can bypass protectheaders and checkcontenttype enforcement by modifying Content-Type, charset, and redirect headers through setHeader(), repeated setContentType() calls, charset APIs, and Servlet 6.1 redirect overloads, exploiting stale configuration. An attacker can inject persistent scripts if they can influence included component behavior.
Affected products
- Apache Sling Engine before 3.0.4
Timeline
- 2026-11-05: disclosed