Horizon Alert
Summary of the vulnerability and why it matters
An authentication bypass vulnerability has been identified in the DIGEST authenticator for Apache Tomcat, a widely used web server. This issue could potentially allow attackers to replay authenticated requests, which could have significant implications for systems that rely on this authentication method for security. The main concern at this stage is to confirm whether our deployed systems are affected by this vulnerability and to what extent.
- Bypass authentication by replaying requests.
- Widely used web server may be at risk.
- Confirm relevance and exposure to Apache Tomcat.
Attack Path
How an attacker could exploit the issue
An attacker could exploit a vulnerability in Apache Tomcat's DIGEST authenticator by replaying a previously valid authentication request. This is possible if the client's nonce count is at the upper boundary of the replay window when a request is made. If successful, this could allow the attacker to bypass authentication.
- No authentication required.
- Replay an authenticated request.
- Bypass authentication.
Live Threat
Current exploitation, exposure, and threat context
When supported by the advisory, an attacker could bypass authentication in Apache Tomcat's DIGEST authenticator, allowing for replayable requests under specific conditions related to the replay window and nonce count. This could potentially impact system access and service integrity.
- Authentication bypass could occur.
- Replayable requests may be used.
- Unauthorized access could result.
Operational Fix
Recommended remediation, mitigation, and detection steps
The Apache Tomcat DIGEST authenticator's authentication bypass vulnerability requires immediate attention from teams managing web application infrastructure. Owners of Tomcat instances, platform engineering, and security operations should collaborate to identify all deployments, assess their exposure to unauthenticated network access, and prioritize remediation. This initial assessment will inform the risk-based planning for applying necessary updates or implementing mitigating controls.
- Platform and application teams own remediation.
- Verify Tomcat network exposure and critical services.
- Plan and coordinate urgent security updates.
