CVE-2026-23794: Apache Syncope: Reflected XSS on Enduser Login

[Francesco Chicchiriccò <ilgrosso () apache org>]

Severity: important 

Affected versions:

- Apache Syncope (org.apache.syncope.client.idrepo:syncope-client-idrepo-common-ui) 3.0 through 3.0.15
- Apache Syncope (org.apache.syncope.client.idrepo:syncope-client-idrepo-common-ui) 4.0 through 4.0.3

Description:

Reflected XSS in Apache Syncope's Enduser Login page.
An attacker that tricks a legitimate user into clicking a malicious link and logging in to Syncope Enduser could steal 
that user's credentials.

This issue affects Apache Syncope: from 3.0 through 3.0.15, from 4.0 through 4.0.3.

Users are recommended to upgrade to version 3.0.16 / 4.0.4, which fix this issue.

Credit:

Kasper Karlsson (finder)
Karin Taliga (finder)

References:

https://syncope.apache.org/
https://www.cve.org/CVERecord?id=CVE-2026-23794