Apache Airflow FAB CVE-2026-46745

LDAP authentication must be actively configured in the Apache Airflow FAB Auth Manager - specifically, auth_type must be set to AUTH_LDAP and valid LDAP connection parameters (auth_ldap_server, auth_ldap_uid_field, etc.) must be present in the Airflow configuration. Deployments using other authentication backends (OAuth, OpenID, password-based) are not affected. The CVSS vector AV:N/AC:L/PR:N/UI:N confirms that once LDAP auth is in use, exploitation requires no authentication, no special privileges, and no user interaction - a remote attacker can directly target the login endpoint. Exploitation is limited to versions of apache-airflow-providers-fab prior to 3.6.4; the specific Python methods _search_ldap and _ldap_get_nested_groups in override.py are the vulnerable code paths as confirmed by the patch diff.

The CVSS 5.3 Medium score (AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N) reflects network-reachable, unauthenticated exploitation with low attack complexity and no user interaction required, but only partial confidentiality impact and no integrity or availability loss per the vector. EPSS at 0.17% (37th percentile) indicates a low current probability of observed exploitation in the wild, consistent with SSVC exploitation status of 'none' and absence from CISA KEV. However, SSVC flags the vulnerability as automatable, meaning adversaries can script login attempts at scale against LDAP-configured Airflow deployments. The 'Authentication Bypass' tag introduces potential impact beyond the CVSS C:L score - LDAP injection can in some configurations allow an attacker to manipulate filter logic to satisfy authentication checks, which would be an integrity impact not fully captured in the CVSS scoring. This discrepancy between the CVSS I:N rating and the authentication bypass tag should be independently verified against the vendor advisory. Overall, real-world priority is moderate: medium-severity for most deployments, elevated for internet-exposed Airflow instances with LDAP auth where unauthenticated access paths are a primary concern.

An attacker targeting an internet-exposed Apache Airflow instance with LDAP authentication sends a crafted HTTP login request where the username field contains LDAP filter metacharacters - for example, *)(uid=*))(|(uid=* - causing the unsanitized filter string to always evaluate as true against the directory, bypassing credential validation. Alternatively, the attacker uses injection payloads to enumerate directory attributes by observing differential authentication responses, exfiltrating user data such as email addresses, group memberships, or other LDAP attributes. No public POC has been identified, but the vulnerability class is well-understood and the fix diff makes the injection points explicit.