CVE-2026-3194: Chia Blockchain Auth Bypass Vulnerability

CVE-2026-3194 Overview

A missing authentication vulnerability has been discovered in Chia Blockchain 2.1.0, affecting the RPC Server Master Passphrase Handler component. Specifically, the send_transaction and get_private_key functions lack proper authentication checks, potentially allowing a local attacker to access sensitive wallet operations without providing valid credentials.

The vulnerability requires local access to the system and has high attack complexity, making exploitation difficult. However, a proof-of-concept has been published, increasing the risk for systems with inadequate host security measures. The vendor has acknowledged this behavior, stating it is "by design" and that users are responsible for host security.

Critical Impact

Local attackers with system access can bypass authentication on the RPC server to access wallet functions including send_transaction and get_private_key, potentially leading to unauthorized cryptocurrency transactions and private key exposure.

Affected Products

• Chia Blockchain 2.1.0
• RPC Server Master Passphrase Handler component
• Functions: send_transaction and get_private_key

Discovery Timeline

• 2026-02-25 - CVE-2026-3194 published to NVD
• 2026-02-25 - Last updated in NVD database

Technical Details for CVE-2026-3194

Vulnerability Analysis

This vulnerability falls under CWE-287 (Improper Authentication), indicating that the affected RPC Server functions fail to properly verify the identity of users before granting access to sensitive wallet operations. The send_transaction and get_private_key endpoints in the Master Passphrase Handler component do not enforce authentication requirements, allowing any process with local access to invoke these functions.

The local attack vector limits the exposure to scenarios where an attacker has already gained access to the host system. However, in multi-user environments, shared systems, or cases where malware has compromised the machine, this vulnerability could be exploited to drain cryptocurrency wallets or extract private keys.

Root Cause

The root cause is missing authentication enforcement in the RPC Server's Master Passphrase Handler. The send_transaction and get_private_key functions do not validate caller identity or require passphrase authentication before processing requests. This design decision appears intentional according to the vendor's response, placing security responsibility on users to maintain host-level access controls.

Attack Vector

The attack requires local access to the system running Chia Blockchain. An attacker must be able to communicate with the RPC server's local interface, typically by having a process running on the same machine. The exploitation is described as difficult due to the local access requirement and high attack complexity.

The attacker could craft RPC requests to the send_transaction endpoint to initiate unauthorized cryptocurrency transfers, or call get_private_key to extract wallet private keys without knowing the master passphrase. A proof-of-concept demonstrating this authentication bypass has been published to a GitHub PoC Repository.

Detection Methods for CVE-2026-3194

Indicators of Compromise

• Unexpected RPC calls to send_transaction or get_private_key endpoints from unauthorized processes
• Unusual cryptocurrency transactions not initiated by the wallet owner
• Evidence of local processes querying the Chia RPC server without proper authentication
• Log entries showing RPC endpoint access from unexpected user contexts or PIDs

Detection Strategies

• Monitor RPC server logs for unauthorized access attempts to sensitive endpoints
• Implement process-level auditing to track which applications communicate with the Chia daemon
• Deploy endpoint detection solutions to identify suspicious process communication patterns
• Review wallet transaction history for unauthorized transfers

Monitoring Recommendations

• Enable verbose logging on the Chia RPC server to capture all endpoint access
• Set up alerts for any send_transaction or get_private_key calls outside of expected usage patterns
• Monitor system authentication logs for signs of local privilege escalation that could precede exploitation
• Implement file integrity monitoring on Chia Blockchain installation directories

How to Mitigate CVE-2026-3194

Immediate Actions Required

• Restrict local access to systems running Chia Blockchain to trusted users only
• Implement host-based firewall rules to limit RPC server access
• Review and harden system access controls on machines hosting Chia wallets
• Consider moving Chia wallets to dedicated, isolated systems with strict access policies

Patch Information

No official patch is available. The vendor has stated this behavior is "by design" and that users are responsible for host security. The bug bounty submission was rejected with this reasoning. Users should implement compensating controls as described below.

For additional technical details, refer to the VulDB entry #347750.

Workarounds

• Deploy the Chia Blockchain on dedicated, single-user systems to minimize local attack surface
• Use operating system-level access controls to restrict which processes can communicate with the RPC server
• Implement network segmentation to isolate cryptocurrency infrastructure
• Consider using hardware wallets for high-value holdings instead of software-based wallets
• Regularly audit local user accounts and remove unnecessary access privileges

# Configuration example
# Restrict RPC server access using host-based firewall rules
# On Linux systems, limit access to localhost only
sudo iptables -A INPUT -p tcp --dport 8555 -s 127.0.0.1 -j ACCEPT
sudo iptables -A INPUT -p tcp --dport 8555 -j DROP

# Ensure Chia runs under a dedicated, non-privileged user account
sudo useradd -r -s /bin/false chia-service
sudo chown -R chia-service:chia-service ~/.chia