Nebula‑mesh is a self‑hosted control plane for Slack Nebula mesh virtual private network. In versions before 0.3.2, the generator interpolates operator‑supplied ListenHost and TunDevice fields raw into a text/template that produces the agent’s config.yml. The advanced override handler accepts these values with only strings.TrimSpace, performing no character or shape validation. This lack of sanitization allows a malicious operator to inject arbitrary YAML into the agent configuration, potentially enabling privilege escalation or remote code execution when the agent runs with elevated privileges. The weakness corresponds to CWE‑94, code injection.

juev’s nebula‑mesh control plane service, versions prior to 0.3.2, are affected. Users running the open‑source project version lower than 0.3.2 who enable host advanced overrides are vulnerable. The issue is fixed in release 0.3.2 and later.

The CVSS score of 8.7 indicates high severity. The EPSS score is under 1%, suggesting that exploitation is unlikely at present. The vulnerability is not listed in CISA’s KEV catalog. Attackers would need to supply a crafted ListenHost or TunDevice value in an advanced override request; because the value is processed without sanitization, YAML injection can modify agent behavior. Proper validation or upgrading mitigates the risk.