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Vulnerability · Published May 20, 2026 · Assigned by redhat

CVE-2026-9087Keycloak: cross-session email verification proof not bound to upstream identity in first-broker-login

Medium 6.4

In plain English

A medium-severity authorization bypass via user-controlled key in Red Hat build of Keycloak 26.4 from Red Hat. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 24% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)6.4Medium
Exploit odds (30 days)0.3%top 75.8% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

A flaw was found in Keycloak. The cross-session verification proof is keyed only by (local userId, idpAlias) and is not bound to the upstream identity that was actually verified, so a second upstream account on the same IdP can consume it and get linked to the victim's local account.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Mavenorg.keycloak:keycloak-services26.6.3GHSA-m6qj-3mpp-57v8

Affected products (as reported)

VendorProductVersions
Red Hat Red Hat build of Keycloak 26.4 see references
Red Hat Red Hat build of Keycloak 26.4 see references
Red Hat Red Hat build of Keycloak 26.4 see references
Red Hat Red Hat build of Keycloak 26.4.13 see references
Red Hat Red Hat build of Keycloak 26.6 see references
Red Hat Red Hat build of Keycloak 26.6 see references
Red Hat Red Hat build of Keycloak 26.6 see references
Red Hat Red Hat build of Keycloak 26.6.3 see references

Weakness: CWE-639 · Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:N

References