How severe is CVE-2020-27838?

CVE-2020-27838 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2020-27838 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 18% (97th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-27838?

CVE-2020-27838 primarily affects Redhat Keycloak. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-27838?

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

When was CVE-2020-27838 published?

CVE-2020-27838 was published on 2021-03-08 and last updated on 2026-06-17.

CVE-2020-27838

CVE-2020-27838 is a medium-severity vulnerability in Redhat Keycloak with a CVSS 3.x base score of 6.5. Its EPSS exploit-prediction score of 18% places it in the 97th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-287.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v2: 4.3
EPSS exploit prediction: 18% (97th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-287
Affected product: Redhat Keycloak
Published: 2021-03-08
Last modified: 2026-06-17

Description

A flaw was found in keycloak in versions prior to 13.0.0. The client registration endpoint allows fetching information about PUBLIC clients (like client secret) without authentication which could be an issue if the same PUBLIC client changed to CONFIDENTIAL later. The highest threat from this vulnerability is to data confidentiality.

Frequently asked questions

What is CVE-2020-27838?: A flaw was found in keycloak in versions prior to 13.0.0. The client registration endpoint allows fetching information about PUBLIC clients (like client secret) without authentication which could be an issue if the same PUBLIC client changed to CONFIDENTIAL later. The highest threat from this vulnerability is to data confidentiality.
How severe is CVE-2020-27838?: CVE-2020-27838 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2020-27838 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 18% (97th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-27838?: CVE-2020-27838 primarily affects Redhat Keycloak. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-27838?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2020-27838 published?: CVE-2020-27838 was published on 2021-03-08 and last updated on 2026-06-17.

References

https://bugzilla.redhat.com/show_bug.cgi?id=1906797

Affected products (2)

cpe:2.3:a:redhat:keycloak:*:*:*:*:*:*:*:*
cpe:2.3:a:redhat:single_sign-on:7.0:*:*:*:*:*:*:*

More vulnerabilities in Redhat Keycloak

CVE-2022-4361 — Critical (CVSS 10.0): Keycloak, an open-source identity and access management solution, has a cross-site scripting (XSS) vulnerability in the…
CVE-2022-1245 — Critical (CVSS 9.8): A privilege escalation flaw was found in the token exchange feature of keycloak. Missing authorization allows a client…
CVE-2019-14910 — Critical (CVSS 9.8): A vulnerability was found in keycloak 7.x, when keycloak is configured with LDAP user federation and StartTLS is used…
CVE-2021-20195 — Critical (CVSS 9.6): A flaw was found in keycloak in versions before 13.0.0. A Self Stored XSS attack vector escalating to a complete…
CVE-2022-3782 — Critical (CVSS 9.1): keycloak: path traversal via double URL encoding. A flaw was found in Keycloak, where it does not properly validate…
CVE-2019-14837 — Critical (CVSS 9.1): A flaw was found in keycloack before version 8.0.0. The owner of 'placeholder.org' domain can setup mail server on this…

All CVEs affecting Redhat Keycloak →

Other CWE-287 (Improper Authentication) vulnerabilities

CVE-2026-20317 — Critical (CVSS 10.0): As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco Secure Workload engineering…
CVE-2026-19977 — Critical (CVSS 10.0): A vulnerability was detected in EFM ipTIME A3004T 14.19.0. The affected element is the function…
CVE-2026-59500 — Critical (CVSS 10.0): CWE-287: Improper Authentication
CVE-2024-27253 — Critical (CVSS 10.0): IBM DOORS Next 7.0.3 through 7.0.3 Interim Fix 018 could allow an authenticated user to bypass security logic to…
CVE-2026-56162 — Critical (CVSS 10.0): Improper authentication in Azure SQL Database allows an unauthorized attacker to elevate privileges over a network.
CVE-2026-62825 — Critical (CVSS 10.0): Improper authentication in Azure Key Vault allows an unauthorized attacker to elevate privileges over a network.

Browse all CWE-287 (Improper Authentication) vulnerabilities →