How severe is CVE-2026-18208?

CVE-2026-18208 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2026-18208 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (10th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-18208?

CVE-2026-18208 affects Redhat Build Of Keycloak. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-18208?

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

When was CVE-2026-18208 published?

CVE-2026-18208 was published on 2026-07-31 and last updated on 2026-08-07.

CVE-2026-18208

CVE-2026-18208 is a medium-severity vulnerability in Redhat Build Of Keycloak with a CVSS 3.x base score of 6.5. 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-862.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
EPSS exploit prediction: 0% (10th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-862
Affected product: Redhat Build Of Keycloak
Published: 2026-07-31
Last modified: 2026-08-07

Description

A flaw was found in the OIDC token introspection endpoint of the keycloak-services component. Keycloak is an open-source identity and access management solution used to secure modern applications and services. The issue occurs when a confidential client, configured to receive signed JWT introspection responses, attempts to introspect a token issued for a different audience. Although the endpoint correctly identifies the token as inactive for that client, it still returns the full set of token claims within a signed JWT field. This allows an unauthorized client to bypass audience-based restrictions and access sensitive information contained in the token.

Frequently asked questions

What is CVE-2026-18208?: A flaw was found in the OIDC token introspection endpoint of the keycloak-services component. Keycloak is an open-source identity and access management solution used to secure modern applications and services. The issue occurs when a confidential client, configured to receive signed JWT introspection responses, attempts to introspect a token issued for a different audience. Although the endpoint correctly identifies the token as inactive for that client, it still returns the full set of token claims within a signed JWT field. This allows an unauthorized client to bypass audience-based restrictions and access sensitive information contained in the token.
How severe is CVE-2026-18208?: CVE-2026-18208 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2026-18208 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (10th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-18208?: CVE-2026-18208 affects Redhat Build Of Keycloak. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-18208?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2026-18208 published?: CVE-2026-18208 was published on 2026-07-31 and last updated on 2026-08-07.

References

Affected products (1)

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

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