How severe is CVE-2026-11800?

CVE-2026-11800 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2026-11800 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (8th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-11800?

CVE-2026-11800 affects Redhat Build Of Keycloak. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-11800?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-11800 have an EU (EUVD) identifier?

Yes. CVE-2026-11800 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-39567.

When was CVE-2026-11800 published?

CVE-2026-11800 was published on 2026-06-25 and last updated on 2026-07-01.

CVE-2026-11800

CVE-2026-11800 is a high-severity vulnerability in Redhat Build Of Keycloak with a CVSS 3.x base score of 8.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-347.

Key facts

Severity: High (CVSS 3.x base score 8.1)
EPSS exploit prediction: 0% (8th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-39567
Weakness: CWE-347
Affected product: Redhat Build Of Keycloak
Published: 2026-06-25
Last modified: 2026-07-01

Description

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.

Frequently asked questions

What is 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 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.
How severe is CVE-2026-11800?: CVE-2026-11800 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2026-11800 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (8th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-11800?: CVE-2026-11800 affects Redhat Build Of Keycloak. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-11800?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-11800 have an EU (EUVD) identifier?: Yes. CVE-2026-11800 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-39567.
When was CVE-2026-11800 published?: CVE-2026-11800 was published on 2026-06-25 and last updated on 2026-07-01.

References

Affected products (1)

cpe:2.3:a:redhat:build_of_keycloak:*:*:*:*:*:*:*:*

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