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Fencer Intel
medium 6.5

CVE-2020-27838 json

Keycloak discloses information without authentication

published 5y ago modified 4mo ago also GHSA-pcv5-m2wh-66j3 , EUVD-2022-4746

cvss
6.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
17.9%
EPSS 17.9% chance of exploitation in 30 days, percentile 97%
public exploits
0
none known, plus a Nuclei check

Summary

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.

Patch / fix

  • maven org.keycloak:keycloak-core 13.0.0
  • redhat keycloak 13.0.0
  • keycloak Arch Linux 13.0.0-1

arch linux advisories AVG-1926

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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-2020-27838 updated cvss 5.3

keycloak: Exploiting the client registration API

  • Red Hat Single Sign-On 7 rh-sso7-keycloak rh-sso7-keycloak
    affected: no fix available
  • Red Hat Decision Manager 7 keycloak keycloak Red Hat Fuse 7 keycloak keycloak Red Hat Integration Camel K 1 keycloak keycloak Red Hat OpenShift Application Runtimes keycloak keycloak Red Hat Process Automation 7 keycloak keycloak Red Hat support for Spring Boot keycloak keycloak
    not affected: vulnerable code not present

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

17.87% chance of exploitation in the next 30 days, higher than 97% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

CVSS scores

assigned by version score vector
NVD 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:P/I:N/A:N
GitHub 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

Affected packages

ecosystem package affected fixed in
maven org.keycloak:keycloak-core
<13.0.0
13.0.0

Affected products

  • n/a keycloak

Classification

Weakness

References

Sources

Fencer Intel 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.