CVE-2026-27476: RustFly Command Injection Vulnerability

CVE-2026-27476 Overview

RustFly 2.0.0 contains a critical command injection vulnerability (CWE-78) in its remote UI control mechanism. The application accepts hex-encoded instructions over UDP port 5005 without proper sanitization, allowing attackers to send crafted hex-encoded payloads containing system commands. This vulnerability enables arbitrary command execution on the target system, including the establishment of reverse shells and execution of malicious operations.

Critical Impact

Unauthenticated remote attackers can achieve full system compromise through arbitrary command execution via crafted UDP packets to port 5005.

Affected Products

• RustFly 2.0.0

Discovery Timeline

• 2026-02-19 - CVE-2026-27476 published to NVD
• 2026-02-19 - Last updated in NVD database

Technical Details for CVE-2026-27476

Vulnerability Analysis

This command injection vulnerability exists in the remote UI control functionality of RustFly 2.0.0. The application implements a UDP-based control mechanism on port 5005 that processes hex-encoded instructions. Due to insufficient input validation and sanitization, user-controlled data within these hex-encoded payloads can be interpreted as system commands, allowing attackers to inject and execute arbitrary operations on the underlying operating system.

The vulnerability is particularly dangerous because UDP is a connectionless protocol, making it easier for attackers to spoof source addresses and potentially bypass network-based access controls. The lack of authentication on the control mechanism compounds the risk, as no credentials are required to exploit this flaw.

Root Cause

The root cause is improper input validation (CWE-78: Improper Neutralization of Special Elements used in an OS Command). The remote UI control mechanism fails to properly sanitize hex-encoded instructions before passing them to system command execution functions. Special characters and command separators within the decoded payload are not filtered or escaped, enabling command injection attacks.

Attack Vector

The attack is network-based and requires no authentication or user interaction. An attacker can exploit this vulnerability by:

1. Identifying a RustFly 2.0.0 instance with UDP port 5005 exposed
2. Crafting a malicious hex-encoded payload containing operating system commands
3. Sending the crafted UDP packet to the target on port 5005
4. The vulnerable application decodes the payload and executes the embedded commands with the privileges of the RustFly process

The vulnerability allows for complete system compromise, including data exfiltration, lateral movement, and persistent access through reverse shell establishment. For detailed technical information, refer to the VulnCheck Advisory on RustFly Command Injection.

Detection Methods for CVE-2026-27476

Indicators of Compromise

• Unexpected UDP traffic to port 5005 from external or unauthorized sources
• Unusual process spawning from the RustFly application process
• Evidence of reverse shell connections originating from the system running RustFly
• Suspicious hex-encoded payloads in network traffic destined for UDP port 5005
• Unexpected command execution patterns in system logs coinciding with RustFly activity

Detection Strategies

• Implement network monitoring rules to detect and alert on UDP traffic to port 5005 from untrusted sources
• Deploy host-based intrusion detection to identify anomalous child processes spawned by RustFly
• Use network packet inspection to identify hex-encoded payloads containing shell command patterns
• Monitor for command execution anomalies using EDR solutions such as SentinelOne Singularity

Monitoring Recommendations

• Configure firewall logging to capture all traffic to UDP port 5005
• Enable detailed process auditing on systems running RustFly 2.0.0
• Implement network segmentation monitoring to detect lateral movement attempts following exploitation
• Review system logs for evidence of unauthorized command execution correlated with RustFly process activity

How to Mitigate CVE-2026-27476

Immediate Actions Required

• Block inbound UDP traffic to port 5005 from untrusted networks using firewall rules
• Isolate systems running RustFly 2.0.0 until patching is complete
• Review system logs for evidence of exploitation attempts
• If the remote UI control feature is not required, disable it entirely

Patch Information

Refer to the official vendor channels for updated versions of RustFly that address this command injection vulnerability. Additional technical details are available through the Packet Storm security advisory and the VulnCheck Advisory.

Workarounds

• Implement strict firewall rules to block UDP port 5005 from all untrusted networks
• Use network segmentation to isolate RustFly instances from direct internet exposure
• Deploy a VPN or authenticated proxy layer in front of any systems requiring remote UI control access
• Monitor systems with endpoint detection and response (EDR) solutions to detect exploitation attempts

# Example firewall configuration to block external access to UDP port 5005
# iptables rule to drop incoming UDP traffic on port 5005 from non-local sources
iptables -A INPUT -p udp --dport 5005 -s ! 127.0.0.1 -j DROP

# Alternative: Allow only specific trusted IP addresses
iptables -A INPUT -p udp --dport 5005 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p udp --dport 5005 -j DROP