How severe is CVE-2026-4366?

CVE-2026-4366 has a CVSS 3.x base score of 5.8, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.

Is CVE-2026-4366 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (13th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-4366?

CVE-2026-4366 primarily affects Redhat Build Of Keycloak. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-4366?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-4366 have an EU (EUVD) identifier?

Yes. CVE-2026-4366 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-12762.

When was CVE-2026-4366 published?

CVE-2026-4366 was published on 2026-03-18 and last updated on 2026-06-17.

CVE-2026-4366

CVE-2026-4366 is a medium-severity vulnerability in Redhat Build Of Keycloak with a CVSS 3.x base score of 5.8. 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-918.

Key facts

Severity: Medium (CVSS 3.x base score 5.8)
EPSS exploit prediction: 0% (13th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-12762
Weakness: CWE-918
Affected product: Redhat Build Of Keycloak
Published: 2026-03-18
Last modified: 2026-06-17

Description

A flaw was identified in Keycloak, an identity and access management solution, where it improperly follows HTTP redirects when processing certain client configuration requests. This behavior allows an attacker to trick the server into making unintended requests to internal or restricted resources. As a result, sensitive internal services such as cloud metadata endpoints could be accessed. This issue may lead to information disclosure and enable attackers to map internal network infrastructure.

Frequently asked questions

What is CVE-2026-4366?: A flaw was identified in Keycloak, an identity and access management solution, where it improperly follows HTTP redirects when processing certain client configuration requests. This behavior allows an attacker to trick the server into making unintended requests to internal or restricted resources. As a result, sensitive internal services such as cloud metadata endpoints could be accessed. This issue may lead to information disclosure and enable attackers to map internal network infrastructure.
How severe is CVE-2026-4366?: CVE-2026-4366 has a CVSS 3.x base score of 5.8, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.
Is CVE-2026-4366 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (13th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-4366?: CVE-2026-4366 primarily affects Redhat Build Of Keycloak. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-4366?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-4366 have an EU (EUVD) identifier?: Yes. CVE-2026-4366 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-12762.
When was CVE-2026-4366 published?: CVE-2026-4366 was published on 2026-03-18 and last updated on 2026-06-17.

References

Affected products (4)

cpe:2.3:a:redhat:build_of_keycloak:-:*:*:*:-:*:*:*
cpe:2.3:a:redhat:jboss_enterprise_application_platform:8.0.0:*:*:*:*:*:*:*
cpe:2.3:a:redhat:jboss_enterprise_application_platform_expansion_pack:-:*:*:*:*:*:*:*
cpe:2.3:a:redhat:single_sign-on:7.0:*:*:*:*:*:*:*

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