Keycloak Server-Side Request Forgery via OIDC token endpoint manipulation

CVE-2026-4874 → View on GitHub ↗ View on CVE.org ↗ View on NVD ↗

Description

A flaw was found in Keycloak. An authenticated attacker can perform Server-Side Request Forgery (SSRF) by manipulating the client_session_host parameter during refresh token requests. This occurs when a Keycloak client is configured to use the backchannel.logout.url with the application.session.host placeholder. Successful exploitation allows the attacker to make HTTP requests from the Keycloak server’s network context, potentially probing internal networks or internal APIs, leading to information disclosure.

Basic information

Type
reviewed
Severity
low
Advisory on GitHub
Open advisory ↗
Repository advisory
—
Source code
Browse source ↗
Published (advisory)
2026-03-26 09:30:28 UTC
Updated
2026-04-13 18:35:14 UTC
GitHub reviewed
2026-03-27 20:03:17 UTC
NVD published
2026-03-26 08:16:22 UTC

EPSS Score

Score Percentile
0.02% 6.44%

CVSS Scores

Base score Version Severity Vector
3.1 3.1 —
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/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:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
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:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.

Identifiers

Type Value
GHSA GHSA-22rm-wp4x-v5cx ↗
CVE CVE-2026-4874 ↗

CWEs

CWE id Name
CWE-918 Server-Side Request Forgery (SSRF)

Credits

  • krapovneru (analyst)
  • dnegreira (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-services <= 26.6.0 — —

References

cvelogic Threat Intelligence