CVE-2026-29771: Gravitl Netmaker DOS Vulnerability

CVE-2026-29771 Overview

CVE-2026-29771 is a Denial of Service vulnerability in Gravitl Netmaker, a network management platform that creates networks using WireGuard. Prior to version 1.2.0, the /api/server/shutdown endpoint allows termination of the Netmaker server process via syscall.SIGINT. This allows any user to repeatedly shut down the server, causing cyclic denial of service with approximately 3-second restart intervals.

Critical Impact

Any unauthenticated attacker can repeatedly terminate the Netmaker server, causing persistent service disruption with rapid restart cycles that effectively render the network management platform unusable.

Affected Products

• Gravitl Netmaker versions prior to 1.2.0
• Self-hosted Netmaker deployments with exposed API endpoints
• Enterprise environments utilizing Netmaker for WireGuard network management

Discovery Timeline

• 2026-03-07 - CVE-2026-29771 published to NVD
• 2026-03-12 - Last updated in NVD database

Technical Details for CVE-2026-29771

Vulnerability Analysis

This vulnerability stems from improper resource shutdown (CWE-404) in the Netmaker API implementation. The /api/server/shutdown endpoint exposes critical server control functionality without proper authentication or authorization checks. When this endpoint is accessed, it triggers a syscall.SIGINT signal that gracefully terminates the Netmaker server process.

The exploitation mechanism is particularly concerning because it requires no authentication, allowing any network-reachable attacker to invoke the shutdown function. The attack surface is further amplified by the server's automatic restart behavior, which creates a predictable 3-second window between shutdown and recovery, enabling attackers to script continuous denial of service attacks.

Root Cause

The root cause is the lack of authentication and authorization controls on the /api/server/shutdown endpoint. This represents a fundamental access control failure where a privileged administrative function was exposed without proper security constraints. The endpoint directly invokes system-level process termination (syscall.SIGINT) without validating whether the requesting entity has administrative privileges to perform such an action.

Attack Vector

The attack vector is network-based and requires no user interaction or special privileges. An attacker with network access to the Netmaker API can send HTTP requests to the vulnerable endpoint, triggering immediate server termination. The attack can be automated to continuously monitor for server restarts and immediately invoke shutdown again, creating a persistent denial of service condition.

The vulnerability allows for cyclic exploitation where an attacker can establish a simple loop that detects server availability and immediately terminates it, maintaining a sustained service outage with minimal attacker resources. For technical details, see the GitHub Security Advisory.

Detection Methods for CVE-2026-29771

Indicators of Compromise

• Repeated HTTP requests to /api/server/shutdown endpoint from external or unexpected IP addresses
• Abnormal server restart patterns with approximately 3-second intervals between restarts
• Log entries showing multiple SIGINT signals received in rapid succession
• Increased network traffic to API endpoints from single sources without valid authentication tokens

Detection Strategies

• Monitor API access logs for requests to /api/server/shutdown endpoint, especially from unauthenticated sources
• Implement alerting on server process restarts that occur more frequently than expected operational patterns
• Deploy web application firewall (WAF) rules to detect and block suspicious requests to administrative endpoints
• Analyze network traffic for patterns consistent with automated shutdown request loops

Monitoring Recommendations

• Configure real-time alerting for any access attempts to the /api/server/shutdown endpoint
• Establish baseline metrics for server uptime and alert on deviations indicating potential DoS activity
• Implement centralized logging for all Netmaker API requests with retention for forensic analysis
• Deploy network-level monitoring to identify sources generating high volumes of API requests

How to Mitigate CVE-2026-29771

Immediate Actions Required

• Upgrade Gravitl Netmaker to version 1.2.0 or later immediately
• Implement network-level access controls to restrict API access to trusted networks or IP ranges
• Deploy reverse proxy or WAF rules to block access to the /api/server/shutdown endpoint pending upgrade
• Review access logs for evidence of exploitation attempts prior to patching

Patch Information

This vulnerability has been patched in Netmaker version 1.2.0. Organizations should upgrade to this version or later to remediate the vulnerability. The patch implements proper authentication and authorization checks on the shutdown endpoint. For detailed patch information, refer to the GitHub Security Advisory.

Workarounds

• Deploy network segmentation to restrict access to the Netmaker API from untrusted networks
• Configure firewall rules to explicitly deny access to /api/server/shutdown from external sources
• Implement API gateway or reverse proxy authentication as an additional security layer
• Consider temporarily disabling public API access until the patch can be applied

# Example: Block access to shutdown endpoint using iptables
iptables -A INPUT -p tcp --dport 8081 -m string --string "/api/server/shutdown" --algo bm -j DROP

# Example: Nginx reverse proxy configuration to block endpoint
location /api/server/shutdown {
    deny all;
    return 403;
}