CVE-2026-65948 Overview
Apache Ranger versions up to and including 2.8.0 contain a missing brute-force protection weakness in the UnixAuth authentication module. The flaw is tracked as CWE-307: Improper Restriction of Excessive Authentication Attempts. Attackers can submit unlimited authentication attempts against the UnixAuth endpoint over the network without triggering account lockout or rate limiting. The Apache Ranger project notes that UnixAuth is not a recommended option for production deployments. Users should upgrade to version 2.9.0, which fixes the issue.
Critical Impact
Unrestricted authentication attempts against UnixAuth allow remote attackers to conduct offline-style password guessing at network speed, potentially compromising Ranger administrative accounts.
Affected Products
- Apache Ranger versions <= 2.8.0 (UnixAuth module)
- Apache Ranger deployments configured with UnixAuth as an authentication provider
- Fixed in Apache Ranger 2.9.0
Discovery Timeline
- 2026-08-10 - CVE-2026-65948 published to NVD
- 2026-08-12 - Last updated in NVD database
Technical Details for CVE-2026-65948
Vulnerability Analysis
Apache Ranger is a centralized framework for defining, administering, and managing security policies across the Hadoop ecosystem. The UnixAuth module authenticates users against local Unix system accounts on the Ranger host. This vulnerability stems from the absence of throttling, account lockout, or progressive delay mechanisms on failed authentication attempts through the UnixAuth path.
Without brute-force protection, an unauthenticated remote attacker can repeatedly submit credential pairs at high volume. The attack requires no user interaction and no prior privileges. Successful exploitation grants the attacker access under the guessed Unix account, which in a Ranger deployment can lead to policy manipulation and downstream access to protected Hadoop resources.
The Apache project explicitly states that UnixAuth is not a recommended authentication provider for production deployments. Organizations that have retained it for lab or legacy reasons remain exposed until they upgrade or switch providers.
Root Cause
The root cause is a missing security control [CWE-307]. The UnixAuth authentication handler does not track failed login counts per account or per source, and it does not enforce lockout thresholds or exponential backoff. This allows attackers to iterate through credential dictionaries against the service without operational cost.
Attack Vector
The attack vector is network-based against the Apache Ranger admin authentication interface. An attacker enumerates valid Unix usernames on the Ranger host and submits sequential password guesses through the UnixAuth login flow. Automated tooling can drive thousands of attempts per minute against weak or reused credentials. See the Apache mailing list announcement and the Openwall OSS-Security disclosure for the project's authoritative description of the issue.
Detection Methods for CVE-2026-65948
Indicators of Compromise
- High volume of failed authentication events in Ranger admin logs originating from a single source IP or a small set of source IPs.
- Successful UnixAuth logins immediately following bursts of failed attempts for the same account.
- Ranger policy or user-management changes occurring shortly after anomalous authentication activity.
Detection Strategies
- Parse Ranger admin logs (ranger-admin.log, access_log) for repeated AUTH FAILED entries per user and per source over short time windows.
- Correlate Ranger authentication events with Unix account activity on the Ranger host, watching for lateral use of the same credentials.
- Alert on any authentication provider configured as UNIX in ranger-admin-site.xml since production use is discouraged by the project.
Monitoring Recommendations
- Forward Ranger admin and audit logs to a centralized SIEM and build rate-based rules for authentication failures per account.
- Monitor for privileged Ranger operations such as policy edits, user role changes, and service definition updates immediately after login events.
- Track network connections to the Ranger admin port from unexpected internal or external sources.
How to Mitigate CVE-2026-65948
Immediate Actions Required
- Upgrade Apache Ranger to version 2.9.0 or later, which addresses the missing brute-force protection.
- Disable UnixAuth and switch to a supported authentication provider such as LDAP, Active Directory, or Kerberos, consistent with Apache Ranger production guidance.
- Rotate credentials for any Unix accounts that were reachable through the UnixAuth interface.
- Restrict network access to the Ranger admin interface to trusted management networks only.
Patch Information
Apache Ranger 2.9.0 fixes CVE-2026-65948 by adding brute-force protection to the UnixAuth authentication module. Refer to the Apache Ranger mailing list announcement and the Openwall OSS-Security posting for the vendor advisory and upgrade guidance.
Workarounds
- Replace UNIX authentication with LDAP, Active Directory, or Kerberos in ranger-admin-site.xml by setting ranger.authentication.method to a non-UNIX value.
- Place the Ranger admin endpoint behind a reverse proxy or web application firewall that enforces IP-based rate limiting and account lockout.
- Restrict inbound access to the Ranger admin port using host-based firewalls or network ACLs until the upgrade is completed.
# Configuration example: switch Ranger from UnixAuth to LDAP in ranger-admin-site.xml
# <property>
# <name>ranger.authentication.method</name>
# <value>LDAP</value>
# </property>
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
