CVE-2025-10547: Vigor Router DrayOS RCE Vulnerability

CVE-2025-10547 Overview

CVE-2025-10547 is a critical uninitialized memory use vulnerability affecting Vigor Routers running DrayOS. The flaw exists in the HTTP CGI request arguments processing component, where an uninitialized variable can be leveraged by attackers to achieve remote code execution (RCE) through memory corruption. This network-accessible vulnerability requires no authentication or user interaction, making it particularly dangerous for internet-facing router deployments.

Critical Impact

Unauthenticated remote attackers can exploit this uninitialized variable vulnerability to execute arbitrary code on affected Vigor Routers, potentially leading to complete device compromise, network infiltration, and persistent backdoor access.

Affected Products

• DrayTek Vigor Routers running DrayOS (specific models listed in vendor advisory)
• DrayOS firmware versions prior to patched releases
• Network appliances with exposed HTTP management interfaces

Discovery Timeline

• 2025-10-03 - CVE-2025-10547 published to NVD
• 2025-11-04 - Last updated in NVD database

Technical Details for CVE-2025-10547

Vulnerability Analysis

This vulnerability stems from the use of an uninitialized variable within the HTTP CGI request arguments processing logic of DrayOS. When processing malformed or specially crafted HTTP requests, the affected component fails to properly initialize memory before use. This uninitialized memory may contain attacker-controllable data or predictable patterns that can be manipulated to corrupt memory structures.

The uninitialized variable vulnerability affects the CGI handler responsible for parsing HTTP request arguments. When exploited, attackers can influence the control flow of the application by manipulating memory contents, ultimately achieving arbitrary code execution with the privileges of the web server process running on the router.

Root Cause

The root cause is improper memory initialization in the HTTP CGI argument parsing routines. The vulnerable code path fails to initialize a variable before it is used in subsequent operations, allowing the variable to retain arbitrary or predictable values from previous stack or heap allocations. This programming error violates secure coding practices that mandate all variables be initialized before use, particularly in memory-unsafe languages commonly used in embedded firmware development.

Attack Vector

The attack is network-based and requires no authentication. An attacker can send specially crafted HTTP requests to the router's web management interface. The malicious requests contain arguments designed to trigger the uninitialized variable condition. By carefully controlling the memory state prior to the vulnerable operation, attackers can influence program execution and achieve code execution.

The exploitation process involves:

1. Identifying an exposed DrayOS HTTP management interface
2. Crafting HTTP requests with specific argument patterns to trigger the uninitialized variable path
3. Leveraging memory layout predictability to inject malicious payloads
4. Achieving arbitrary code execution on the router

For detailed technical information about the vulnerability mechanism, refer to the DrayTek Security Advisory and CERT Vulnerability Note #294418.

Detection Methods for CVE-2025-10547

Indicators of Compromise

• Unusual HTTP requests to router management interfaces with malformed or oversized CGI arguments
• Unexpected process spawning or network connections originating from the router
• Router configuration changes without administrator action
• Presence of unauthorized firmware modifications or persistent backdoors
• Anomalous outbound traffic patterns from router IP addresses

Detection Strategies

• Monitor HTTP access logs for suspicious CGI requests with abnormal parameter patterns
• Implement network intrusion detection rules to identify exploitation attempts targeting DrayOS routers
• Deploy SentinelOne Singularity for network edge visibility to detect post-exploitation behaviors
• Establish baseline behavior for router management interfaces and alert on deviations

Monitoring Recommendations

• Enable comprehensive logging on all DrayOS router management interfaces
• Configure SIEM alerting for HTTP requests to router administration ports from untrusted sources
• Implement egress filtering to detect compromised routers communicating with command-and-control infrastructure
• Regularly audit router configurations for unauthorized changes

How to Mitigate CVE-2025-10547

Immediate Actions Required

• Apply the latest firmware updates from DrayTek that address CVE-2025-10547
• Restrict access to router HTTP management interfaces to trusted IP addresses only
• Disable remote management access if not required
• Place management interfaces on isolated network segments
• Monitor for exploitation attempts using network security tools

Patch Information

DrayTek has released security updates addressing this vulnerability. Administrators should consult the DrayTek Security Advisory for specific patch versions for their router models. The CERT Vulnerability Note #294418 provides additional guidance on remediation steps and affected product identification.

Workarounds

• Implement access control lists (ACLs) to restrict HTTP management interface access to trusted networks only
• Disable HTTP-based management and use console or SSH for administration where possible
• Deploy a firewall or VPN in front of router management interfaces to add an authentication layer
• Consider network segmentation to isolate potentially vulnerable devices from critical infrastructure

# Example: Restrict management access to specific IP ranges (syntax varies by model)
# Consult DrayTek documentation for your specific router model
# Management > Access Control > Allow Management from LAN Only
# Or configure firewall rules to block WAN access to management ports (80, 443)