Keycloak-services: keycloak-services: saml idp-initiated broker login bypasses link-only restriction

Summary

CVE	CVE-2026-16442
State	PUBLISHED
Assigner	redhat
Source Priority	CVE Program / NVD first with legacy fallback
Published	2026-08-05 16:16:52 UTC
Updated	2026-08-05 19:17:26 UTC
Description	A flaw was found in the SAML broker component of Keycloak, which is used to manage identity federation and user authentication. The issue occurs because the IdP-initiated Single Sign-On endpoint fails to check if a provider is restricted to account linking only. This allows an attacker with control over a linked upstream identity to bypass login restrictions and gain full access to a local user account.

Risk And Classification

Primary CVSS: v3.1 7.4 HIGH from [email protected]

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

Problem Types: CWE-346 | CWE-346 Origin Validation Error

Version	Source	Type	Score	Severity	Vector
3.1	[email protected]	Secondary	7.4	HIGH	`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N`
3.1	CNA	CVSS	7.4	HIGH	`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N`

CVSS v3.1 Breakdown

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

None

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

Vendor Declared Affected Products

Source	Vendor	Product	Version	Platforms
CNA	Red Hat	Red Hat Build Of Keycloak 26.4	unaffected 26.4.14-1 * rpm	Not specified
CNA	Red Hat	Red Hat Build Of Keycloak 26.4	unaffected 26.4-22 * rpm	Not specified
CNA	Red Hat	Red Hat Build Of Keycloak 26.4	unaffected 26.4-22 * rpm	Not specified
CNA	Red Hat	Red Hat Build Of Keycloak 26.4.14	Not specified	Not specified
CNA	Red Hat	Red Hat Build Of Keycloak 26.4.14	Not specified	Not specified
CNA	Red Hat	Red Hat Build Of Keycloak 26.6	unaffected 26.6.5-1 * rpm	Not specified
CNA	Red Hat	Red Hat Build Of Keycloak 26.6	unaffected 26.6-11 * rpm	Not specified
CNA	Red Hat	Red Hat Build Of Keycloak 26.6	unaffected 26.6-11 * rpm	Not specified
CNA	Red Hat	Red Hat Build Of Keycloak 26.6.5	Not specified	Not specified
CNA	Red Hat	Red Hat Build Of Keycloak 26.6.5	Not specified	Not specified
CNA	Red Hat	Red Hat Build Of Keycloak 26.6.5	Not specified	Not specified
CNA	Red Hat	Red Hat Data Grid 8	Not specified	Not specified
CNA	Red Hat	Red Hat JBoss Enterprise Application Platform Expansion Pack	Not specified	Not specified
CNA	Red Hat	Red Hat Single Sign-On 7	Not specified	Not specified

References

Reference	Source	Link	Tags
access.redhat.com/errata/RHSA-2026:50846	[email protected]	access.redhat.com
access.redhat.com/errata/RHSA-2026:50847	[email protected]	access.redhat.com
access.redhat.com/errata/RHSA-2026:50848	[email protected]	access.redhat.com
access.redhat.com/errata/RHSA-2026:50849	[email protected]	access.redhat.com
access.redhat.com/security/cve/CVE-2026-16442	[email protected]	access.redhat.com
bugzilla.redhat.com/show_bug.cgi	[email protected]	bugzilla.redhat.com
CVE Program record	CVE.ORG	www.cve.org	canonical
NVD vulnerability detail	NVD	nvd.nist.gov	canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Red Hat would like to thank Paul Bottinelli (Trail of Bits) for reporting this issue. (en)

Additional Advisory Data

Source	Time	Event
CNA	2026-07-17T18:19:22.000Z	Reported to Red Hat.
CNA	2026-08-05T02:02:00.000Z	Made public.

Workarounds

CNA: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.

There are currently no legacy QID mappings associated with this CVE.