CVE-2026-76186 in Airflow
Summary
by MITRE • 09/16/2026
Apache Airflow Keycloak provider: from Airflow 3.3 the Keycloak auth manager takes a user's identity from the signed Airflow session token but takes the Keycloak access and refresh tokens used for every authorization decision from separate, unauthenticated cookies, and never checks that the two describe the same subject. A user who holds any valid Airflow login of their own, together with another subject's Keycloak access or refresh token obtained out of band, can pair the two: Airflow then authorizes requests with the foreign token's privileges while the session identity, audit log and cache keys continue to name the attacker's own account. The refresh path re-issues an Airflow session token for the original identity carrying the foreign tokens, so the mismatched pairing survives across sessions.
Affects deployments running Airflow 3.3 or later with the Keycloak auth manager. Earlier versions carried the Keycloak tokens inside the signed session token, so the binding existed and was lost when they moved into separate cookies.
Users of apache-airflow-providers-keycloak are recommended to upgrade to version 0.10.0 or later, which binds the cookie-supplied tokens to the session identity.
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Analysis
by VulDB Data Team • 09/16/2026
The vulnerability in Apache Airflow versions 3.3 and later utilizing the Keycloak authentication manager represents a critical failure in token binding and identity consistency within the web application security model. This flaw stems from an architectural change where Keycloak access and refresh tokens were moved into separate, unauthenticated cookies rather than being embedded directly inside the signed Airflow session token as was done in earlier versions. In secure implementations, the authentication state must be cryptographically bound to the user's identity to prevent impersonation or privilege escalation. By decoupling these elements, Apache Airflow inadvertently created a scenario where the system fails to verify that the Keycloak tokens presented by the client actually correspond to the subject identified in the signed session token. This separation of concerns without proper validation introduces a severe integrity violation allowing attackers to manipulate authorization decisions independently of their authenticated identity.
The operational impact of this vulnerability is significant, enabling an attacker who possesses any valid Airflow login credentials for their own account to escalate privileges by pairing that legitimate session with another user's Keycloak access or refresh tokens obtained through out-of-band means such as token theft from other systems or network interception. When the attacker submits a request, Airflow validates the signed session token and establishes an audit log entry under the attacker's identity while simultaneously using the foreign Keycloak tokens to determine authorization permissions for that specific action. Consequently, the system grants access based on the privileges associated with the stolen external tokens rather than those of the logged-in user. This mismatch persists across sessions because the refresh mechanism re-issues a new Airflow session token tied to the original attacker identity while retaining the foreign Keycloak tokens in the cookies, effectively creating a persistent backdoor that allows continued unauthorized access under a false guise without detection by standard audit logs which only record the legitimate account name.
From a technical classification perspective, this vulnerability aligns with CWE-287 Improper Authentication and CWE-345 Insufficient Verification of Data Authenticity as it involves failing to ensure that authentication credentials match the expected identity context. It also maps closely to MITRE ATT&CK technique T1098.004 SSH Unauthorized Access via Expired or Invalid Credentials if viewed through the lens of token reuse, but more accurately reflects T1528 Steal Application Access Token where an attacker leverages stolen tokens to gain unauthorized access. The core issue is a lack of cryptographic binding between the session identity and the authorization credentials, which violates fundamental principles of secure state management in web applications. This flaw allows for privilege escalation without requiring additional exploitation vectors beyond obtaining valid Keycloak tokens from any source, making it particularly dangerous in environments where token leakage might occur via logs, browser history, or other side channels.
To mitigate this risk, organizations running Apache Airflow 3.3 or later with the Keycloak auth manager must immediately upgrade to apache-airflow-providers-keycloak version 0.10.0 or later. This updated release corrects the architectural flaw by re-establishing a secure binding between the cookie-supplied tokens and the session identity, ensuring that authorization decisions are always made based on credentials belonging to the authenticated user. Until this patch is applied, administrators should consider restricting access to Keycloak endpoints, implementing strict logging monitoring for anomalous permission patterns, or temporarily disabling the external token reliance if feasible within their deployment constraints. Regular audits of authentication logs and enforcement of least-privilege principles can help detect potential exploitation attempts where audit trails show a user performing actions inconsistent with their typical role profile despite appearing legitimate in session data.