EUVD-2026-45176
GHSA-63wm-fvw8-h2hp
Severity by source
AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:L/A:N
Network-delivered but requires code interception (AC:H) and a low-privilege attacker position (PR:L); victim must initiate OAuth flow (UI:R); token issuance yields high confidentiality impact with minor integrity impact from cross-client redemption.
Primary rating from Vendor (redhat).
CVSS VectorNVD
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:L/A:N
Lifecycle Timeline
2DescriptionNVD
A flaw was found in the keycloak-services component of Red Hat Build of Keycloak. The issue occurs because OAuth 2.0 authorization codes are not properly bound to the client that originally requested them. An attacker who can intercept an authorization code can modify it to be redeemed by their own client, potentially allowing them to obtain access tokens for a victim's identity.
AnalysisAI
Authorization code injection in Red Hat Build of Keycloak's keycloak-services component enables a network-positioned attacker to hijack OAuth 2.0 flows by intercepting and cross-client redeeming authorization codes. Because codes are not cryptographically bound to the originating client, an attacker who obtains a victim's in-flight code can submit it using their own registered client credentials and receive access tokens tied to the victim's identity. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Three concurrent prerequisites are required for exploitation: (1) the attacker must hold at least low-privilege access - likely a legitimately registered OAuth client or an authenticated presence within the Keycloak realm (PR:L from CVSS vector); (2) the attacker must be capable of intercepting a victim's authorization code in transit, for example via a network interception position, an open redirect misconfiguration in a registered redirect_uri allowing code exfiltration to an attacker-controlled endpoint, or a referrer header leak from a non-HTTPS redirect; and (3) a victim must actively initiate an OAuth 2.0 authorization code flow (UI:R from CVSS vector). … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 5.4 (Medium) base score reflects a technically achievable but non-trivial attack path. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker who operates a registered OAuth client in the same Keycloak realm, or who holds a man-in-the-middle network position, observes a victim's authorization code as it transits an insecurely configured redirect_uri or referrer header. The attacker immediately submits the intercepted code to Keycloak's token endpoint using their own client_id and client_secret, and because the server does not verify that the code was issued to that specific client, it issues valid access tokens representing the victim's identity. … |
| Remediation | Patch available per vendor advisory - administrators should apply the update published at https://access.redhat.com/security/cve/CVE-2026-16089 as the primary remediation; no specific fixed version number is confirmed in the available data, so the Red Hat advisory must be monitored directly for the patched release. … Detailed patch versions, workarounds, and compensating controls in full report. |
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External POC / Exploit Code
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