Public proof of conceptFix available

CVE-2026-9086

Q: Is CVE-2026-9086 actively exploited?

Active exploitation of CVE-2026-9086 has not been confirmed. Its EPSS score was 0.8% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2026-9086?

CVE-2026-9086 has a CVSS v3 base score of 7.3 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N.

A public proof of concept exists; no exploitation attested.

Published2026-06-25
Fixed in26.6.4 · 26.4.13
WeaknessCWE-79

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

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.

Timeline

dates in UTC

2026-06-2517:17CVE publishedNVD
2026-10-2319:23First public proof of conceptPoC-in-GitHub

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-9086?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-9086?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD · OSV

Redhat build of keycloak

Branch	Affected	Fixed in	Source
26.6	≥ 26.6, < 26.6.4	26.6.4	NVD
26.6	≥ 26.6.0, < 26.6.4	26.6.4	OSV
26.4	≥ 26.4, < 26.4.13	26.4.13	NVD
26.4	≥ 26.4.0, < 26.4.13	26.4.13	OSV

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Update Redhat build of keycloak to 26.6.4 · 26.4.13

Detection

read 2026-10-23 19:25 UTC

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: 1 repository, unverifiedSaku0512/CVE-2026-9086-poc

Sources

NVDCVE recordread 2026-10-23
CISA-ADPSSVC decisionnone2026-06-25
OpenCVESSVC decisionnone—
CNACVSS 3.17.3read 2026-10-23
CNAweakness (CWE)CWE-79read 2026-10-23
FIRST EPSSEPSS score0.8 %2026-10-22
PoC-in-GitHubproof of concept1read 2026-10-23
OSVaffected packages—

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N
Published: 2026-06-25
Last Modified: 2026-07-15
NVD status: Analyzed

Frequently asked questions

What is CVE-2026-9086?

Is CVE-2026-9086 actively exploited?

Active exploitation of CVE-2026-9086 has not been confirmed. Its EPSS score was 0.8% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-9086?

CVE-2026-9086 has a CVSS v3 base score of 7.3 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N.

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