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CVE-2026-92857

Keycloak-services: keycloak-services: dcr protocol mapper config not validated, allowing iat holders to forge sub and aud claims in signed tokens

High8.1EPSS 0.36%
Published
Updated
Reserved
Assigned by
redhat

Description

Keycloak provides a Dynamic Client Registration feature that allows users with specific tokens to register their own applications. A flaw in how Keycloak validates these registration requests allows an attacker to create a malicious application that forges identity information. By mapping their own user profile details to protected fields like the user ID (sub) or intended audience (aud), an attacker can generate signed security tokens that make them appear to be a different user. This could allow an attacker to impersonate other users or gain unauthorized access to services that rely on these tokens for identity verification.

Scores

CVSS scores of CVE-2026-92857, by who scored it
Scored byCVSSScoreVector
redhatCNA (assigner)3.1High8.1CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
NVDNVD · Awaiting Analysis3.1High8.1CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
EPSS (exploitation in 30 days)
0.36% · top 70% of all CVEs (7 Nov 2026)
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The list uses the assigner's score when there is one, then CISA's, then NVD's: High 8.1.

Weakness

Affected products

What to do

Workaround: 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. --- CME Mitigation Guidance (2026-11-06) --- Disclaimer: The following mitigation solutions are provided as a courtesy, pending the application of an official patch. This content was generated utilizing AI tools in conjunction with data from https://cmetaxonomy.org. Customers are advised to independently evaluate and test these temporary mitigations within their own infrastructure. The highest-value action is to validate protocol mapper claim.name configurations during Dynamic Client Registration to deny mapping to reserved identity claims: upgrade to Red Hat build of Keycloak 26.4.17, 26.6.8 (or the corresponding fixed Red Hat builds), which validate and reject protocol mapper configurations in Dynamic Client Registration that assign reserved claims to claim.name, closing all 2 injection vectors (Dynamic Client Registration protocol mapper configuration mapping user profile attributes to the sub claim, Dynamic Client Registration protocol mapper configuration mapping user profile attributes to the aud claim). Until patched, this is a concern on Keycloak deployments enabling Dynamic Client Registration where users possess an Initial Access Token and editable realm profile attributes, so restrict issuance of Initial Access Tokens, monitor new client registrations, and restrict user capabilities to edit profile attributes. As a compensating measure, detect unauthorized Dynamic Client Registration creations and protocol mapper changes by alerting on configuration drift against declared realm baselines and log Dynamic Client Registration events and mapper configurations to a SIEM to identify unauthorized clients mapping reserved token claims. These controls limit blast radius and contain exploitation, but they do not fix the underlying unvalidated protocol mapper claim.name defect — apply the upstream patch to fully remediate. Highest-impact CME: CME-1315 Allowlist-Preferred Input Validation (Deny-by-Default Filtering) (high)

References (6)

Sources

The same CVE in the primary databases and aggregators, to check against.

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Record last updated .