Keycloak Authorization Bypass vulnerability

Description

Due to a permissive regular expression hardcoded for filtering allowed hosts to register a dynamic client, a malicious user with enough information about the environment could benefit and jeopardize an environment with this specific Dynamic Client Registration with TrustedDomain configuration previously unauthorized.

Acknowledgements:

Special thanks to Bastian Kanbach for reporting this issue and helping us improve our security.

Basic information

Type
reviewed
Severity
medium
Advisory on GitHub
Open advisory ↗
Repository advisory
Open repository advisory ↗
Source code
Browse source ↗
Published (advisory)
2024-04-17 17:33:29 UTC
Updated
2024-04-25 22:23:50 UTC
GitHub reviewed
2024-04-17 17:33:29 UTC
NVD published
2024-04-25

EPSS Score

Score Percentile
1.31% 79.79%

CVSS Scores

Base score Version Severity Vector
5.4 3.1
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.

Identifiers

CWEs

CWE id Name
CWE-625 Permissive Regular Expression

Affected packages (2)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem Package Vulnerable range First patched Vulnerable functions
maven org.keycloak:keycloak-services < 22.0.10 22.0.10
maven org.keycloak:keycloak-services >= 23.0.0, < 24.0.3 24.0.3

References

cvelogic Threat Intelligence