CVE-2026-3517: Progress ADC RCE Vulnerability

CVE-2026-3517 Overview

CVE-2026-3517 is an OS Command Injection vulnerability affecting Progress ADC Products, specifically the LoadMaster appliance. This vulnerability enables an authenticated attacker with "Geo Administration" permissions to execute arbitrary commands on the underlying system by exploiting unsanitized input in the addcountry command within the API. Command injection flaws of this nature can lead to complete system compromise when successfully exploited.

Critical Impact

Authenticated attackers with Geo Administration privileges can achieve full remote code execution on LoadMaster appliances, potentially compromising network traffic management infrastructure and enabling lateral movement within the adjacent network.

Affected Products

• Progress LoadMaster ADC Products
• Progress ADC API with Geo Administration functionality
• LoadMaster appliances with vulnerable firmware versions

Discovery Timeline

• 2026-04-20 - CVE-2026-3517 published to NVD
• 2026-04-20 - Last updated in NVD database

Technical Details for CVE-2026-3517

Vulnerability Analysis

This vulnerability is classified under CWE-77 (Improper Neutralization of Special Elements used in a Command). The flaw exists within the API layer of Progress LoadMaster ADC products, specifically in the handling of the addcountry command used by the Geo Administration functionality.

The attack requires adjacency to the network where the LoadMaster appliance resides and high-level privileges (Geo Administration permissions). However, once these prerequisites are met, the attacker faces low complexity in exploiting the vulnerability. The scope is changed, meaning successful exploitation can impact resources beyond the vulnerable component itself, affecting confidentiality, integrity, and availability of the entire appliance and potentially connected systems.

Root Cause

The root cause of CVE-2026-3517 is improper input sanitization within the addcountry command handler in the LoadMaster API. When processing country-related configuration parameters, the application fails to properly validate and sanitize user-supplied input before incorporating it into system commands. This allows specially crafted input containing shell metacharacters or command separators to break out of the intended command context and execute arbitrary OS-level commands with the privileges of the LoadMaster service.

Attack Vector

The attack vector for this vulnerability is through the adjacent network, requiring the attacker to have network proximity to the target LoadMaster appliance. The attacker must possess valid credentials with "Geo Administration" permissions to access the vulnerable API endpoint.

The exploitation flow involves:

1. Authenticating to the LoadMaster management interface with Geo Administration credentials
2. Accessing the API endpoint responsible for the addcountry functionality
3. Injecting malicious OS commands through unsanitized input fields
4. The injected commands execute with the privileges of the LoadMaster application process

The vulnerability allows command chaining through common shell metacharacters, enabling attackers to execute arbitrary commands beyond the intended functionality of the country configuration feature. For technical details on the exploitation mechanism, refer to the Progress Security Advisory.

Detection Methods for CVE-2026-3517

Indicators of Compromise

• Unusual API requests to the addcountry endpoint containing shell metacharacters such as ;, |, &&, or backticks
• Unexpected process spawning from the LoadMaster application process
• Anomalous outbound network connections originating from the LoadMaster appliance
• Authentication logs showing access to Geo Administration functions from unexpected sources

Detection Strategies

• Monitor LoadMaster API access logs for requests to geographic administration endpoints with suspicious parameters
• Implement network-based detection rules for command injection patterns in HTTP/HTTPS traffic to LoadMaster management interfaces
• Deploy endpoint detection on LoadMaster appliances to identify unexpected child processes or command execution
• Audit Geo Administration permission assignments to identify potentially compromised or unnecessary privileged accounts

Monitoring Recommendations

• Enable verbose logging on LoadMaster API endpoints, particularly for Geo Administration functions
• Configure alerts for API requests containing common command injection characters in parameter values
• Monitor process execution chains on LoadMaster appliances for anomalous behavior
• Review authentication logs for Geo Administration access from unusual IP addresses or at unusual times

How to Mitigate CVE-2026-3517

Immediate Actions Required

• Review and audit all accounts with "Geo Administration" permissions, removing unnecessary privilege grants
• Restrict network access to LoadMaster management interfaces to trusted administrative networks only
• Implement additional network segmentation to limit adjacent network exposure
• Monitor for exploitation attempts while preparing to apply vendor patches

Patch Information

Progress has released a security advisory addressing this vulnerability along with several related issues (CVE-2026-3518, CVE-2026-3519, CVE-2026-4048, CVE-2026-21876). Administrators should consult the Progress Security Advisory for specific patch versions and upgrade instructions applicable to their LoadMaster deployment.

Workarounds

• Limit Geo Administration permissions to only essential personnel and service accounts
• Implement strict network access controls to isolate the LoadMaster management interface from untrusted network segments
• Deploy web application firewalls (WAF) or API gateways with command injection detection capabilities in front of the LoadMaster API
• Consider disabling the Geo Administration feature if not actively required until patches can be applied

# Example: Restrict management interface access via firewall rules
# Allow management access only from trusted admin network
iptables -A INPUT -p tcp --dport 443 -s 10.0.100.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP