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.
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.
Update org.keycloak:keycloak-server-spi-private to 26.6.3; org.keycloak:keycloak-services to 26.6.3 if you use the affected versions. Test the change in a non-production environment first.
Local check
hol-guard supply-chain scanKeycloak Vulnerable to Improper Validation of Specified Quantity in Input affects org.keycloak:keycloak-server-spi-private (maven), org.keycloak:keycloak-services (maven). Severity is medium. 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.
AI coding agents often install or upgrade packages automatically in maven. A medium vulnerability in a dependency can be pulled into a project through a normal install or update without a human reviewing the change, expanding the blast radius from a single package to every agent workspace that depends on it.
| Package | Affected range | Fixed version |
|---|---|---|
| org.keycloak:keycloak-server-spi-privatemaven |
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.
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.
Update org.keycloak:keycloak-server-spi-private to 26.6.3; org.keycloak:keycloak-services to 26.6.3 if you use the affected versions. Test the change in a non-production environment first.
Local check
hol-guard supply-chain scanKeycloak Vulnerable to Improper Validation of Specified Quantity in Input affects org.keycloak:keycloak-server-spi-private (maven), org.keycloak:keycloak-services (maven). Severity is medium. 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.
AI coding agents often install or upgrade packages automatically in maven. A medium vulnerability in a dependency can be pulled into a project through a normal install or update without a human reviewing the change, expanding the blast radius from a single package to every agent workspace that depends on it.
| Package | Affected range | Fixed version |
|---|---|---|
| org.keycloak:keycloak-server-spi-privatemaven |
| <26.6.3 |
| 26.6.3 |
| org.keycloak:keycloak-servicesmaven | <26.6.3 | 26.6.3 |
|---|
Fixed versions are reported by the source feed; confirm compatibility before updating.
Reported by GitHub Security Advisories (ghsa).
HOL Guard can help your team review package activity against supported protection paths.
Explore HOL Guard| <26.6.3 |
| 26.6.3 |
| org.keycloak:keycloak-servicesmaven | <26.6.3 | 26.6.3 |
|---|
Fixed versions are reported by the source feed; confirm compatibility before updating.
Reported by GitHub Security Advisories (ghsa).
HOL Guard can help your team review package activity against supported protection paths.
Explore HOL Guard