CVE-2026-16093: Keycloak provides a mechanism called Client Policies to enforce security requirements on clients, such as requiring them to use signed JWTs for authentication. A flaw was discovere

mediumCVSS 5.4CVE-2026-16093

Keycloak provides a mechanism called Client Policies to enforce security requirements on clients, such as requiring them to use signed JWTs for authentication. A flaw was discovered where this enforcement can be bypassed. An attacker with valid client credentials can provide a fake, unsigned assertion header that tricks the system into thinking the policy requirements have been met. This allows the attacker to authenticate using simpler methods like a client secret even when the administrator has mandated more secure, signed assertions.

Details

Source: NVD Recent CVEs (US · database · site)
Severity: medium — CVSS 5.4
Published: 2026-07-17
Last updated: 2026-07-21
Exploitation: Not in CISA KEV at last sync

Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-16093

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-160930.19% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 9% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-16093	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

medium[NEW] [UNPATCHED] [medium] Keycloak: Multiple vulnerabilitiescert-bund

Recent advisories for Keycloak provides a

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

mediumCVE-2026-18215: Keycloak provides a way to let users log in using Microsoft accounts while restricting access …nvd · 2026-07-31
lowCVE-2026-18206: A flaw was found in the keycloak-services component of Keycloak, which provides identity and a…nvd · 2026-07-31
mediumCVE-2026-18201: Keycloak provides a way to manage identity providers and organizations through its administrat…nvd · 2026-07-29
mediumCVE-2026-15943: A flaw was found in the Keycloak keycloak-services component, which handles the management of …nvd · 2026-07-17
mediumCVE-2026-12388: A flaw was found in the Identity Provider (IdP) mapper component of Keycloak, which is used to…nvd · 2026-06-30