CVE-2026-18569Network attack vector

Forced logout via unsigned backchannel tokens

Published Aug 4, 2026 · Updated Aug 4, 2026

Improper signature verification in Red Hat build of Keycloak allows remote attackers to force brokered users offline via forged logout tokens. The OIDC backchannel logout endpoint accepts an alg=none token when the identity provider has validateSignature disabled. Exploitation requires that non-default setting plus the provider issuer, broker client ID, and a user's upstream subject or session ID; it terminates targeted online or offline sessions.

CVSS severity3.7
Low
EPSS probability0.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Improper signature verification in Red Hat build of Keycloak allows remote attackers to force brokered users offline via forged logout tokens. The OIDC backchannel logout endpoint accepts an alg=none token when the identity provider has validateSignature disabled. Exploitation requires that non-default setting plus the provider issuer, broker client ID, and a user's upstream subject or session ID; it terminates targeted online or offline sessions.

The record

CVE
CVE-2026-18569
Published
Aug 4, 2026
Updated
Aug 4, 2026
Vendor
389 Directory Server
Product
Red Hat build of Keycloak
Classifications
CWE-347
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 4, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Affected versions are unavailable in this record. Check the vendor advisory for version and patch details.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

389 Directory Server · Red Hat build of KeycloakAffected versions are unavailable in this record.

Published CVSS scores

3.7Red Hat, Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-347Improper Verification of Cryptographic Signature

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo