VDB-431423 · CVE-2026-103863 · GCVE-0-2026-103863

Apache Sling Engine up to 3.0.3 setHeader cross site scripting

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
3.4	$0-$5k	0.00+

Summaryinfo

A vulnerability classified as problematic has been found in Apache Sling Engine up to 3.0.3. This vulnerability affects the function setHeader. The manipulation leads to cross site scripting. This vulnerability is listed as CVE-2026-103863. The attack may be initiated remotely. There is no available exploit. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in Apache Sling Engine up to 3.0.3. It has been rated as problematic. This issue affects the function setHeader. The manipulation with an unknown input leads to a cross site scripting vulnerability. Using CWE to declare the problem leads to 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. Impacted is integrity. The summary by CVE is:

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.

It is possible to read the advisory at lists.apache.org. The identification of this vulnerability is CVE-2026-103863 since 10/01/2026. The exploitation is known to be easy. The attack may be initiated remotely. It demands that the victim is doing some kind of user interaction. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 11/05/2026). The attack technique deployed by this issue is T1059.007 according to MITRE ATT&CK.

Upgrading to version 3.0.4 eliminates this vulnerability.

Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Vendor

Apache

Name

Sling Engine

Version

License

open-source

Website

Vendor: https://www.apache.org/

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 3.5
VulDB Meta Temp Score: 3.4

VulDB Base Score: 3.5
VulDB Temp Score: 3.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

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Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Cross site scripting
CWE: CWE-79 / CWE-94 / CWE-74
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Sling Engine 3.0.4

Timelineinfo

10/01/2026 CVE reserved
11/05/2026 +35 days Advisory disclosed
11/05/2026 +0 days VulDB entry created
11/05/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: apache.org

Advisory: lists.apache.org
Status: Confirmed

CNA: apache
CVE: CVE-2026-103863 (🔒)

GCVE (CVE): GCVE-0-2026-103863
GCVE (VulDB): GCVE-100-431423

Entryinfo

Created: 11/05/2026 13:51
Changes: 11/05/2026 13:51 (54)
Complete: 🔍
Cache ID: 216::103