CVE-2020-27838
Keycloak discloses information without authentication
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- Required
What an attacker can affect
- Confidentiality
- High
- Integrity
- None
- Availability
- None
Exploit likelihood
What each source reports
NVD Score used
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.
- Record
CVE-2020-27838- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N - CVSS 2.0
- 4.3 Medium
AV:N/AC:M/Au:N/C:P/I:N/A:N - Weakness
- CWE-287
- Updated
- 2026-11-02
CVE List No score
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.
- Record
CVE-2020-27838- Weakness
- CWE-287
- Updated
- 2026-11-02
EUVDEUVD-2022-4746 No score
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.
- Record
EUVD-2022-4746- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-pcv5-m2wh-66j3
Keycloak discloses information without authentication
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.
- Record
GHSA-pcv5-m2wh-66j3- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N - Weakness
- CWE-287
- Updated
- 2026-11-02
OSV
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.
- Record
CVE-2020-27838- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N - Updated
- 2026-11-02
OSVGHSA-pcv5-m2wh-66j3
Keycloak discloses information without authentication
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.
- Record
GHSA-pcv5-m2wh-66j3- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N - Weakness
- CWE-287
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
org.keycloak:keycloak-coreMaven |
before 13.0.0 | 13.0.0 |
org.keycloak:keycloak-coreMaven |
before 13.0.0, plus listed versions 1.0-alpha-11.0-alpha-1-120620131.0-alpha-21.0-alpha-31.0-alpha-4 Show 45 moreShow less1.0-beta-11.0-beta-1-201505211.0-beta-1-201505231.0-beta-21.0-beta-31.0-beta-41.0-final1.0-rc-11.0-rc-21.0.1.Final1.0.2.Final1.0.3.Final1.0.4.Final1.0.5.Final1.1.0.Beta11.1.0.Beta21.1.0.Final1.1.1.Final1.2.0.Beta11.2.0.CR11.2.0.Final1.3.0.Final1.3.1.Final1.4.0.Final1.5.0-Final1.5.0.Final1.5.1.Final1.6.0.Final1.6.1.Final1.7.0.CR11.7.0.Final1.8.0.Alpha11.8.0.CR11.8.0.CR21.8.0.CR31.8.0.Final1.8.1.Final1.9.0.CR11.9.0.Final1.9.1.Final1.9.2.Final1.9.3.Final1.9.4.Final1.9.5.Final1.9.7.Final |
13.0.0 |
Public exploits
Links only. Every CVE stores no exploit code.
| Source | Link | Date |
|---|---|---|
| Nuclei | KeyCloak - Information Exposure | |
| PoC in GitHub | Cappricio-Securities/CVE-2020-27838 | 2024-05-14 |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases, products | EUVD | |
| first indexed | CVE List, GitHub Advisories, Nuclei, NVD, OSV, PoC in GitHub |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2020-27838 is a medium vulnerability (CVSS 6.5) in Keycloak, published March 8, 2021. Public exploit code exists. EPSS puts the chance of exploitation in the next 30 days at 17.9%, the 97th percentile. Fixed in org.keycloak:keycloak-core 13.0.0.
References
Left out here: 72 versions. The JSON record has them.