Keycloak logs sensitive headers

Description

A flaw was found in Keycloak. When the logging format is configured to a verbose, user-supplied pattern (such as the pre-defined 'long' pattern), sensitive headers including Authorization and Cookie are disclosed to the logs in cleartext. An attacker with read access to the log files can extract these credentials (e.g., bearer tokens, session cookies) and use them to impersonate users, leading to a full account compromise.

Patches are available, see:

  • https://github.com/keycloak/keycloak/releases/tag/26.4.11
  • https://github.com/keycloak/keycloak/releases/tag/26.5.6
  • https://github.com/keycloak/keycloak/releases/tag/26.6.0

Basic information

Type
reviewed
Severity
medium
Advisory on GitHub
Open advisory ↗
Repository advisory
Source code
Browse source ↗
Published (advisory)
2026-02-10 12:30:28 UTC
Updated
2026-04-08 21:55:48 UTC
GitHub reviewed
2026-02-11 19:08:55 UTC
NVD published
2026-02-10

EPSS Score

Score Percentile
0.01% 0.26%

CVSS Scores

Base score Version Severity Vector
5.0 3.1
CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
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:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.

Identifiers

CWEs

CWE id Name
CWE-117 Improper Output Neutralization for Logs

Credits

  • julianladisch (analyst)
  • eminaktas (analyst)

Affected packages (1)

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

Ecosystem Package Vulnerable range First patched Vulnerable functions
maven org.keycloak:keycloak-quarkus-server < 26.5.6 26.5.6

References

cvelogic Threat Intelligence