CVE-2026-108549: cc-connect Authentication Bypass Vulnerability

CVE-2026-108549 Overview

CVE-2026-108549 is a missing authentication vulnerability [CWE-306] in cc-connect through version 1.5.0. The flaw resides in the MAX platform adapter webhook mode implemented in platform/max/max.go. When no webhook_secret is configured, the webhook listener on port 8080 accepts unauthenticated updates from remote senders. Attackers can forge update payloads containing an allowed or administrative user_id and trigger privileged commands such as /shell on the host. Successful exploitation grants remote command execution with the privileges of the cc-connect process.

Critical Impact

Unauthenticated remote attackers reaching the MAX webhook listener on port 8080 can execute arbitrary shell commands by spoofing an administrator user_id in forged webhook updates.

Affected Products

• cc-connect versions up to and including 1.5.0
• Deployments running the MAX platform adapter in webhook mode
• Instances configured without a webhook_secret value

Discovery Timeline

• 2026-10-10 - CVE-2026-108549 published to NVD
• 2026-10-13 - Last updated in NVD database

Technical Details for CVE-2026-108549

Vulnerability Analysis

The MAX platform adapter in cc-connect exposes a webhook listener on TCP port 8080 to receive updates from the MAX messaging platform. In the handler defined around platform/max/max.go lines 287 to 305, the code processes incoming update payloads and derives the sender identity from the user_id field inside the request body. The handler does not require an authenticated transport, a signed payload, or a shared secret unless the operator explicitly sets webhook_secret in configuration.

When webhook_secret is absent, any network client that can reach port 8080 can submit arbitrary JSON updates. The adapter trusts the client-supplied user_id and matches it against the allowlist and administrator list used by the command dispatcher. Administrative commands including /shell are then executed on the underlying host.

Root Cause

The root cause is a missing authentication check on a privileged ingress path. The webhook sender identity is read from the untrusted request body rather than verified cryptographically against the MAX platform. The configuration treats webhook_secret as optional, so default or incomplete deployments silently fall into an unauthenticated mode. See the GitHub cc-connect Code Reference for the affected handler.

Attack Vector

An attacker needs network reachability to port 8080 of the cc-connect host and knowledge of a user_id present in the operator allowlist or admin list. The attacker crafts an HTTP POST request that mimics a legitimate MAX webhook update, embeds the chosen user_id, and includes a message body invoking a privileged command such as /shell. The handler executes the command on the host and returns the output through the normal response path. Further technical context is published in the VulnCheck Advisory on cc-connect.

Detection Methods for CVE-2026-108549

Indicators of Compromise

• Unexpected inbound HTTP POST requests to TCP port 8080 on hosts running cc-connect
• Webhook payloads containing /shell or other command prefixes paired with administrator user_id values
• Child processes spawned by the cc-connect binary that execute shell interpreters such as /bin/sh, /bin/bash, or cmd.exe
• Outbound connections initiated by cc-connect to attacker-controlled infrastructure immediately after webhook traffic

Detection Strategies

• Inspect reverse-proxy and web server logs for POST requests to the MAX webhook path originating from non-MAX source ranges
• Correlate webhook request timestamps with process creation events on the cc-connect host to identify command execution
• Alert on cc-connect instances exposing port 8080 to untrusted networks without a configured webhook_secret

Monitoring Recommendations

• Enable process execution telemetry on hosts running cc-connect and baseline the normal command set
• Monitor for new listening sockets or configuration changes to platform/max adapter files
• Capture full HTTP request bodies for the webhook endpoint to support forensic review of forged updates

How to Mitigate CVE-2026-108549

Immediate Actions Required

• Configure a strong webhook_secret value for every MAX adapter instance and verify the handler rejects unauthenticated requests
• Restrict inbound access to TCP port 8080 using network ACLs, firewall rules, or a reverse proxy that enforces source IP allowlisting for MAX platform ranges
• Audit the allowlist and administrator user_id configuration and remove unused or shared identifiers
• Review host command history and cc-connect logs for evidence of /shell or other administrative command invocations

Patch Information

No fixed version is identified in the enriched advisory data at the time of writing. Operators running cc-connect through 1.5.0 should track the GitHub cc-connect Repository and GitHub cc-connect Issue #1968 for an upstream fix and apply it as soon as it is released.

Workarounds

• Set a non-empty webhook_secret in the MAX adapter configuration to force signature verification on incoming updates
• Place the webhook listener behind a reverse proxy that terminates TLS and enforces mutual authentication or IP allowlisting
• Disable the MAX webhook mode and use polling mode if webhook delivery is not operationally required
• Run cc-connect as a dedicated low-privilege user to limit the impact of /shell command execution

# Configuration example: enforce a webhook secret and bind to loopback
# behind a reverse proxy that validates source IPs
export MAX_WEBHOOK_SECRET="$(openssl rand -hex 32)"
export MAX_WEBHOOK_BIND="127.0.0.1:8080"

# Example iptables rule restricting port 8080 to a trusted upstream
iptables -A INPUT -p tcp --dport 8080 -s 203.0.113.10 -j ACCEPT
iptables -A INPUT -p tcp --dport 8080 -j DROP