# CVE-2026-16103 — Red Hat Build of Keycloak

> As of 2026-08-31, CVE-2026-16103 is a MEDIUM-severity vulnerability in Red Hat Build of Keycloak, CVSS v3.1 4.3, EPSS 0.3% (25.9th percentile). Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2026-16103, most recently “CVE-2026-17059: Keycloak Admin REST API Broken Object-Level Authorization Exposes User PII”.

**Last updated:** 2026-08-31

## What is CVE-2026-16103?

A flaw was found in the keycloak-services component of Keycloak. This issue is an incomplete fix for CVE-2026-9798, where brute-force protection checks were added to the Client-Initiated Backchannel Authentication (CIBA) initiation handler but were omitted from the token redemption handler. This allows an attacker with valid client credentials to obtain access and refresh tokens for a user account that has been locked due to brute-force protection, provided the authentication request was started before the lockout occurred and was approved by the user.

The record classifies CVE-2026-16103 under weakness classes [CWE-305](https://intel.threadlinqs.com/cwe/CWE-305), [CWE-841](https://cwe.mitre.org/data/definitions/841.html). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs a user to take an action first. 4 affected-product entries are recorded, across 1 vendor, listed below. The identifier was first published 103 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 4.3 — MEDIUM (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N`)
- **EPSS (FIRST):** 0.3% probability of exploitation in the next 30 days, higher than 25.9% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 3.2/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-07-17, last modified 2026-08-31

## Is CVE-2026-16103 being exploited?

It currently carries a trending score of 20 in the Threadlinqs vulnerability feed.

## Affected products and versions

- [Red Hat](https://intel.threadlinqs.com/vendors/red-hat): Build of Keycloak, Data Grid 8, JBoss Enterprise Application Platform Expansion Pack, Single Sign-On 7

## How to fix CVE-2026-16103

No vendor patch reference has been recorded for CVE-2026-16103 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-16103

1 tracked threat in the Threadlinqs corpus references CVE-2026-16103, either in the campaign’s CVE list or as an indicator on the campaign record.

- [CVE-2026-17059: Keycloak Admin REST API Broken Object-Level Authorization Exposes User PII](https://intel.threadlinqs.com/threat/TL-2026-1796) — MEDIUM · 2026-07-31

## Sources

Enriched from CVE.org, FIRST EPSS. Last verified by Threadlinqs on 2026-10-10.

**Third-party advisory**

- [access.redhat.com — vdb entry](https://access.redhat.com/security/cve/CVE-2026-16103)
- [bugzilla.redhat.com — issue tracking](https://bugzilla.redhat.com/show_bug.cgi?id=2501736)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-16103
Full detection coverage and IOCs for threats exploiting CVE-2026-16103 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp