CVE Tools
Sign in

CVE-2026-9704

Keycloak: keycloak: privilege escalation due to oversized subject_token jwt

Published: May 27, 2026Updated: Jun 26, 2026 Sources: CVE List NVDCWE-1284
6.8MEDIUM
NVD MITRE
EPSS Score
0.3%
Top 75.5%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available
Self-Check
OpenVAS

Description

A flaw was found in Keycloak. An authenticated user with low privileges can exploit this vulnerability by sending an oversized subject_token JSON Web Token (JWT) to the TokenEndpoint. When the token exceeds a 4000-character limit, it is silently dropped, causing the system to fall back to client credentials. This allows the user to gain the permissions of the client's service account, leading to privilege escalation.

No summary for this CVE yet.

CVSS Vector Breakdown

AV:NAC:HPR:LUI:NS:UC:HI:HA:N
Exploitability
AV:NAttack Vector
Network
AC:HAttack Complexity
High
PR:LPrivileges Required
Low
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:HConfidentiality
High
I:HIntegrity
High
A:NAvailability
None
Open in CVSS calculator →

Weaknesses

CWE-1284

Affected Products

Red Hat
commercial·USaka redhat
build of keycloakOn-prem
Operating Systems / linux-distro
Red Hat build of Keycloak 26.4On-premWeb App
Web & CMS Plugins
Red Hat build of Keycloak 26.4.13On-prem
DevTools & CI
Red Hat build of Keycloak 26.6On-prem
Security Products / identity-access-mgmt
Red Hat build of Keycloak 26.6.3On-prem
Security Products / identity-access-mgmt

Exploitability

Official Patch Available
Workaround Available
Is your org exposed to CVE-2026-9704?We can run the check for you — a free external exposure review, no install. Check my exposure

References

https://access.redhat.com/errata/RHSA-2026:25097
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:25098
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:30049
access.redhat.com
and 3 more references View all →

Unlock Complete Vulnerability Intelligence

Get the full picture for CVE-2026-9704 and every CVE in our database. Create a free account — no credit card required.

Create Free Account
Plain-language analysis
Impact assessment and exploitation scenario in plain English
Attack graph visualization
Interactive attack path and kill chain mapping
Exploit details & PoC links
ExploitDB, Metasploit, GitHub PoCs with direct links
Nuclei scanner templates
Ready-to-use vulnerability scanner templates
Full remediation guide
Patch instructions, workarounds, and compliance impact
Interactive AI chat
Ask questions about this vulnerability in natural language
Related vulnerabilities
Semantically similar CVEs and attack patterns
REST API & MCP access
Integrate vulnerability data into your workflows