CVE-2026-9086highCWE-79

CVE-2026-9086: high-severity vulnerability in Red Hat build of Keycloak 26.4

Keycloak: keycloak: cross-site scripting (xss) via case-insensitive uri validation bypass

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41Vexday Risk Score

No sign of exploitation. It has a public proof of concept.

ssvc Attendcvss 7.3epss 0.8%
from disclosure to weapon46 days
Published on NVDJun 25
1st PoC+46d
A flaw was found in Keycloak. A remote attacker with administrative privileges, specifically those with `manage-client` permission or access to client registration endpoints, could bypass client Uniform Resource Identifier (URI) validation. This is achieved by registering a malicious client with a specially crafted redirect URI using a case-insensitive `javascript:` or `data:` scheme. This Cross-Site Scripting (XSS) vulnerability allows for arbitrary code execution in the Keycloak origin when a victim clicks the crafted link, such as in the logout flow or the Admin Console.
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N
Affected products
Red Hat · Red Hat build of Keycloak 26.4Red Hat · Red Hat build of Keycloak 26.4.13Red Hat · Red Hat build of Keycloak 26.6Red Hat · Red Hat build of Keycloak 26.6.4
⚠ Public resources, to assess the exposure of systems you control or are authorized to test. Test only with authorization.
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