CVE-2026-29023: Keygraph Shannon Auth Bypass Vulnerability

CVE-2026-29023 Overview

CVE-2026-29023 is a hardcoded credentials vulnerability affecting Keygraph Shannon, an API routing component. The vulnerability exists because the router configuration contains a hard-coded API key that, when the router component is enabled and exposed to the network, allows unauthenticated attackers to authenticate using the publicly known static key.

An attacker who can reach the router port can proxy requests through the Shannon instance using the victim's configured upstream provider API credentials. This results in unauthorized API usage and potential disclosure of proxied request and response data, essentially allowing attackers to piggyback on legitimate API integrations.

Critical Impact

Attackers can abuse victim API credentials to make unauthorized requests through exposed Shannon router instances, leading to potential API quota exhaustion, unauthorized data access, and exposure of sensitive proxied traffic.

Affected Products

• Keygraph Shannon (versions prior to commit 023cc95)

Discovery Timeline

• 2026-03-09 - CVE CVE-2026-29023 published to NVD
• 2026-03-11 - Last updated in NVD database

Technical Details for CVE-2026-29023

Vulnerability Analysis

This vulnerability falls under CWE-798 (Use of Hard-coded Credentials), a common security weakness where developers embed static authentication credentials directly in source code or configuration files. In the case of Keygraph Shannon, the router component ships with a default API key that remains unchanged across installations.

The fundamental security issue is that any attacker who discovers this hard-coded key—whether through source code review, reverse engineering, or public disclosure—can authenticate to any exposed Shannon router instance. Since the key is static and identical across all installations, compromise of one instance effectively compromises all instances using the default configuration.

The network-accessible nature of the router component means that any Shannon instance with the router enabled and reachable over the network is potentially vulnerable. The attacker does not require any prior access or special privileges to exploit this vulnerability.

Root Cause

The root cause is the inclusion of a static, hard-coded API key in the Shannon router configuration. This key was likely intended for development or testing purposes but was shipped in production code without requiring administrators to generate unique credentials during deployment. This design flaw violates the security principle of unique, per-instance credentials and allows attackers to leverage publicly available information to gain unauthorized access.

Attack Vector

The attack vector is network-based and requires no user interaction. An attacker must be able to reach the Shannon router port over the network. The attack flow involves:

1. The attacker identifies a Shannon instance with the router component enabled and exposed
2. The attacker uses the publicly known hard-coded API key to authenticate to the router
3. Once authenticated, the attacker can proxy requests through the Shannon instance
4. These proxied requests use the victim's configured upstream API credentials, allowing unauthorized API access and potential data exfiltration

The vulnerability allows both unauthorized usage of the victim's API quotas and potential interception of request/response data flowing through the proxy.

Detection Methods for CVE-2026-29023

Indicators of Compromise

• Unexpected authentication attempts to the Shannon router port using the default API key
• Unusual volume of API requests being proxied through Shannon instances
• Requests originating from unexpected source IP addresses being routed through the Shannon proxy
• Log entries showing successful authentications from unknown or suspicious network locations

Detection Strategies

• Monitor Shannon router logs for authentication events, particularly those using the default hard-coded key
• Implement network intrusion detection rules to alert on connections to Shannon router ports from untrusted networks
• Audit deployed Shannon instances to identify which are running vulnerable configurations
• Review API usage metrics for upstream providers to detect anomalous consumption patterns

Monitoring Recommendations

• Enable detailed logging for Shannon router authentication events
• Configure alerts for any successful authentication using the default API key
• Monitor network traffic to Shannon router ports for unusual patterns or source IPs
• Implement rate limiting on the router component to detect and mitigate abuse attempts

How to Mitigate CVE-2026-29023

Immediate Actions Required

• Update Keygraph Shannon to a version containing commit 023cc95 or later
• If unable to update immediately, disable the router component until patching is possible
• Restrict network access to the Shannon router port using firewall rules
• Rotate any API credentials that may have been exposed through compromised Shannon instances

Patch Information

The vulnerability has been addressed in commit 023cc95, which modifies the router authentication mechanism to require unique, user-configured credentials rather than relying on the hard-coded default key. Organizations should update to a version of Shannon that includes this commit.

For detailed information about the fix, refer to the GitHub Pull Request #224 and the specific commit changes. Additional context is available in the GitHub Issue #186 and the VulnCheck Security Advisory.

Workarounds

• Disable the Shannon router component entirely if it is not required for operations
• Implement network segmentation to ensure the router port is not accessible from untrusted networks
• Deploy a reverse proxy or firewall in front of Shannon to add an additional authentication layer
• Monitor for and block connections attempting to use the known default API key