Aviatrix Controller 6.x Unauthenticated Remote Code Execution (RCE) and Directory Traversal Vulnerability (CVE-2021-40870) Analysis & Mitigation Guide
Executive & SecOps Summary
SECOPS ASSESSMENTAviatrix Controller 6.x versions prior to 6.5-1804.1922
Unauthenticated remote attackers can execute arbitrary code with system privileges by exploiting directory traversal and unrestricted file upload vulnerabilities
Immediately upgrade Aviatrix Controller to version 6.5-1804.1922 or later, and restrict external access to the management interface
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
Immediately upgrade the Aviatrix Controller to version 6.5-1804.1922 or later via the admin console or CLI.
# Example command to trigger controller software upgrade via CLI
# (Log in with administrative privileges before execution)
upgrade_controller --version 6.5-1804.19222. Temporary Workaround & Hardening Configuration
If immediate patching is not possible, restrict access to the Aviatrix Controller's HTTPS interface using firewalls or Security Groups to allow only trusted IP addresses.
# Revoke public access and restrict HTTPS (port 443) to a trusted administrative subnet using AWS CLI
aws ec2 revoke-security-group-ingress \
--group-id sg-XXXXXX \
--protocol tcp \
--port 443 \
--cidr 0.0.0.0/0
aws ec2 authorize-security-group-ingress \
--group-id sg-XXXXXX \
--protocol tcp \
--port 443 \
--cidr 192.168.1.0/243. Log Audit & IoC Verification Commands
Inspect web server access logs for unauthorized file uploads and search for newly created executable scripts in the web directories.
# Search access logs for suspicious POST requests to vapi endpoints and PHP executions
grep -E 'POST /.*vapi.*' /var/log/nginx/access.log
grep -E 'GET /.*vapi.*\.php' /var/log/nginx/access.log
# Scan the web root directory for recently modified or created PHP files
find /var/www/ -name '*.php' -mtime -30 -lsStop Exposing VPN Ports to the Internet — Switch to Zero-Trust Access
Eliminate public-facing VPN concentrators and firewall management ports with identity-first Zero-Trust Network Access.
Technical Root Cause & Exploitation Mechanics
1. Vulnerability Overview & Root Cause
This vulnerability (CVE-2021-40870) exists in the file upload functionality of the Aviatrix Controller due to insufficient input validation. An unauthenticated remote attacker can upload files of dangerous types (such as PHP web shells) and leverage directory traversal sequences ('..') in the filename to bypass path restrictions and write files to arbitrary locations within the web root.
2. Exploitation Mechanics & Attack Scenario
An attacker sends a crafted HTTP POST request containing directory traversal sequences in the filename to an unauthenticated upload endpoint. This bypasses security filters and saves an executable script (e.g., a PHP web shell) into a publicly accessible directory like '/vapi/'. The attacker then accesses the uploaded script via an HTTP GET request to execute arbitrary operating system commands on the controller.
3. Infrastructure & Business Impact
Aviatrix Controller serves as the central orchestrator for multi-cloud network infrastructures. Compromising this controller allows attackers to gain full control over cloud network topologies, intercept transit traffic between VPCs/VNets, and potentially extract cloud provider API credentials, leading to catastrophic infrastructure-wide compromise.
Official Vendor Advisories & References
An issue was discovered in Aviatrix Controller 6.x before 6.5-1804.1922. Unrestricted upload of a file with a dangerous type is possible, which allows an unauthenticated user to execute arbitrary code via directory traversal.
Frequently Asked SecOps Questions (CVE-2021-40870)
FAQQ1. How critical is CVE-2021-40870 and is it actively exploited in the wild?
CVE-2021-40870 is rated CVSS 9.8 (CRITICAL) with a 30-day EPSS exploitation probability of 93.0%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2021-40870?
Primary impacted vendors include aviatrix across controller. Scope summary: Aviatrix Controller 6.x versions prior to 6.5-1804.1922
Q3. What temporary mitigations or workarounds exist for CVE-2021-40870 before patching?
[Mitigation] Immediately upgrade Aviatrix Controller to version 6.5-1804.1922 or later, and restrict external access to the management interface Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
Generate an Internal Engineering Notice or CISO Report for CVE-2021-40870
Instantly format this advisory into an executive CISO summary or engineering patch ticket.
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