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Fencer Vulns
medium 4.2

CVE-2020-27826 json

Authentication Bypass in keycloak

published 2021-05-28 5 y ago modified 2026-06-17 4 mo ago also GHSA-m9cj-v55f-8x26 , EUVD-2022-1472

cvss
4.2
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 47%
public exploits
0
none known

Summary

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.

Patch / fix

  • maven org.keycloak:keycloak-core 12.0.0
  • redhat keycloak 12.0.0
  • rh-sso7-keycloak red hat single sign on 7 9.0.10-1.redhat_00001.1.el7sso
  • rh-sso7-keycloak-server red hat single sign on 7 9.0.10-1.redhat_00001.1.el7sso
  • rh-sso7-keycloak red hat single sign on 7 9.0.10-1.redhat_00001.1.el6sso
  • rh-sso7-keycloak-server red hat single sign on 7 9.0.10-1.redhat_00001.1.el6sso
  • rh-sso7-keycloak red hat single sign on 7 9.0.10-1.redhat_00001.1.el8sso
  • rh-sso7-keycloak-server red hat single sign on 7 9.0.10-1.redhat_00001.1.el8sso

red hat advisories RHSA-2020:5527RHSA-2020:5526RHSA-2020:5528

  • keycloak Arch Linux 12.0.0-1

arch linux advisories AVG-1373

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2020-27826 updated cvss 4.2

keycloak: Account REST API can update user metadata attributes

  • Red Hat Single Sign-On 7
    fixed: vendor fix RHSA-2020:5533
  • Red Hat Single Sign-On 7.4 for RHEL 6 Server rh-sso7-keycloak 9.0.10-1.redhat_00001.1.el6sso, rh-sso7-keycloak-server 9.0.10-1.redhat_00001.1.el6sso
    fixed: vendor fix RHSA-2020:5526
  • Red Hat Single Sign-On 7.4 for RHEL 7 Server rh-sso7-keycloak 9.0.10-1.redhat_00001.1.el7sso, rh-sso7-keycloak-server 9.0.10-1.redhat_00001.1.el7sso
    fixed: vendor fix RHSA-2020:5527
  • Red Hat Single Sign-On 7.4 for RHEL 8 rh-sso7-keycloak 9.0.10-1.redhat_00001.1.el8sso, rh-sso7-keycloak-server 9.0.10-1.redhat_00001.1.el8sso
    fixed: vendor fix RHSA-2020:5528

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.57% chance of exploitation in the next 30 days, higher than 47% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 4.2 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N
NVD 2.0 4.9 AV:N/AC:M/Au:S/C:P/I:P/A:N
GitHub 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
maven org.keycloak:keycloak-core
<12.0.0
12.0.0

Affected products

  • n/a keycloak

Classification

Weakness
  • CWE-250 Execution with Unnecessary Privileges

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.