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CVE-2020-27826

Authentication Bypass in keycloak

4.2 MediumFix available

A flaw was found in Keycloak before version 12.0.0 where it is possible to update the user's metadata attributes using Account REST API. This flaw allows an attacker to change its own NameID attribute to impersonate the admin user for any particular application.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
High
Privileges needed
Low
User interaction
None

What an attacker can affect

Confidentiality
Low
Integrity
Low
Availability
None

Exploit likelihood

0.57%Up 0.2 points since May 29, 2021
90%50%10%1%

What each source reports

NVD Score used 4.2

A flaw was found in Keycloak before version 12.0.0 where it is possible to update the user's metadata attributes using Account REST API. This flaw allows an attacker to change its own NameID attribute to impersonate the admin user for any particular application.

Record
CVE-2020-27826
CVSS 3.1
4.2 MediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N
CVSS 2.0
4.9 MediumAV:N/AC:M/Au:S/C:P/I:P/A:N
Weakness
CWE-250
Updated
2026-11-02
CVE List No score

A flaw was found in Keycloak before version 12.0.0 where it is possible to update the user's metadata attributes using Account REST API. This flaw allows an attacker to change its own NameID attribute to impersonate the admin user for any particular application.

Record
CVE-2020-27826
Weakness
CWE-250
Updated
2026-11-02
EUVDEUVD-2022-1472 No score

A flaw was found in Keycloak before version 12.0.0 where it is possible to update the user's metadata attributes using Account REST API. This flaw allows an attacker to change its own NameID attribute to impersonate the admin user for any particular application.

Record
EUVD-2022-1472
Updated
2026-11-03
GitHub AdvisoriesGHSA-m9cj-v55f-8x26 8.8

Authentication Bypass in keycloak

A flaw was found in Keycloak before version 12.0.0 where it is possible to update the user's metadata attributes using Account REST API. This flaw allows an attacker to change its own NameID attribute to impersonate the admin user for any particular application.

Record
GHSA-m9cj-v55f-8x26
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-250
Updated
2026-11-02
OSV 4.2

A flaw was found in Keycloak before version 12.0.0 where it is possible to update the user's metadata attributes using Account REST API. This flaw allows an attacker to change its own NameID attribute to impersonate the admin user for any particular application.

Record
CVE-2020-27826
CVSS 3.1
4.2 MediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N
Updated
2026-11-02
OSVGHSA-m9cj-v55f-8x26 8.8

Authentication Bypass in keycloak

A flaw was found in Keycloak before version 12.0.0 where it is possible to update the user's metadata attributes using Account REST API. This flaw allows an attacker to change its own NameID attribute to impersonate the admin user for any particular application.

Record
GHSA-m9cj-v55f-8x26
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-250
Updated
2026-11-02
OSVRHSA-2020:5526 4.2

Red Hat Security Advisory: Red Hat Single Sign-On 7.4.4 security update on RHEL 6

Record
RHSA-2020:5526
CVSS 3.1
4.2 MediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N
Updated
2026-11-02
OSVRHSA-2020:5527 4.2

Red Hat Security Advisory: Red Hat Single Sign-On 7.4.4 security update on RHEL 7

Record
RHSA-2020:5527
CVSS 3.1
4.2 MediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N
Updated
2026-11-02
OSVRHSA-2020:5528 4.2

Red Hat Security Advisory: Red Hat Single Sign-On 7.4.4 security update on RHEL 8

Record
RHSA-2020:5528
CVSS 3.1
4.2 MediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
org.keycloak:keycloak-core
Maven
 before 12.0.0
12.0.0
org.keycloak:keycloak-core
Maven
 before 12.0.0, plus listed versions
1.0-alpha-11.0-alpha-1-120620131.0-alpha-21.0-alpha-31.0-alpha-4
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1.0-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
12.0.0
rh-sso7-keycloak
Red Hat:red_hat_single_sign_on:7::el6
 before 0:9.0.10-1.redhat_00001.1.el6sso
0:9.0.10-1.redhat_00001.1.el6sso
rh-sso7-keycloak-server
Red Hat:red_hat_single_sign_on:7::el6
 before 0:9.0.10-1.redhat_00001.1.el6sso
0:9.0.10-1.redhat_00001.1.el6sso
rh-sso7-keycloak
Red Hat:red_hat_single_sign_on:7::el7
 before 0:9.0.10-1.redhat_00001.1.el7sso
0:9.0.10-1.redhat_00001.1.el7sso
rh-sso7-keycloak-server
Red Hat:red_hat_single_sign_on:7::el7
 before 0:9.0.10-1.redhat_00001.1.el7sso
0:9.0.10-1.redhat_00001.1.el7sso
rh-sso7-keycloak
Red Hat:red_hat_single_sign_on:7::el8
 before 0:9.0.10-1.redhat_00001.1.el8sso
0:9.0.10-1.redhat_00001.1.el8sso
rh-sso7-keycloak-server
Red Hat:red_hat_single_sign_on:7::el8
 before 0:9.0.10-1.redhat_00001.1.el8sso
0:9.0.10-1.redhat_00001.1.el8sso

History

History
RecordedChangedSources
aliases, productsEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2020-27826 is a medium vulnerability (CVSS 4.2) in Keycloak, published May 28, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.57%, the 47th percentile. Fixed in org.keycloak:keycloak-core 12.0.0.

References

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