CVE-2026-11800: A flaw was found in Keycloak. This JWT algorithm confusion vulnerability in the JWT Authorization Grant flow allows an attacker with valid client credentials to bypass signature ve

highCVSS 8.1CVE-2026-11800

A flaw was found in Keycloak. This JWT algorithm confusion vulnerability in the JWT Authorization Grant flow allows an attacker with valid client credentials to bypass signature verification. By forging an assertion, the attacker can create unauthorized access tokens. This enables the attacker to impersonate any federated user linked to the affected Identity Provider, leading to unauthorized access and potential privilege escalation.

Details

Source: NVD Recent CVEs (US · database · site)
Severity: high — CVSS 8.1
Published: 2026-06-25
Last updated: 2026-07-01
Exploitation: Not in CISA KEV at last sync

Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-11800

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-118000.18% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 8% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-11800	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

high[UPDATE] [high] Keycloak: Multiple vulnerabilitiescert-bund
unknownMultiple vulnerabilities in KeyCloak (June 29, 2026)cert-fr-avis

CVE-2026-11800: A flaw was found in Keycloak. This JWT algorithm confusion vulnerability in the JWT Authorization Grant flow allows an attacker with valid client credentials to bypass signature ve

Details

Exploitation outlook

Referenced CVEs

Same CVEs, other sources

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