CVE-2026-61699: Forgekeep Nebula-Mesh

High severity, CVSS 8.1. EPSS: 0.4% chance of exploitation in the next 30 days.

nebula-mesh is a self-hosted control plane for Slack Nebula mesh VPN. Prior to version 0.7.1, revocation is the only in-band mechanism that isolates a compromised/offboarded host from a Nebula mesh. Because the blocklist never reaches any peer's config.yml, a Blocked host retains full overlay reachability to every peer under its CA (and internal services on the mesh) for up to 30d (agent) / 365d (mobile). An attacker who exfiltrates host.key+host.crt can run stock slackhq/nebula directly, ignore the agent's 403/410 poll responses, and stay connected after the operator revokes the host. Operator-visible state (UI shows blocked, audit log records it) is misleading. This issue has been patched in version 0.7.1.

Affected products

• Forgekeep Nebula-Mesh: before 0.7.1 (fixed in 0.7.1)

Published 2026-09-04. Last modified 2026-09-08.