CVE-2026-61699
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.
What this means for your business
- An attacker can use it remotely, over a network, with an ordinary user login, and without anyone at your company clicking anything.
- FIRST's prediction model gives it a 0.2% chance of attack attempts being seen in the next 30 days, ranking above 16% of all known flaws.
What to do
- 1Ask your IT team or provider whether any of your systems use the affected product.
- 2If you do, follow the vendor's guidance. No patch reference has been published yet.
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Scoring
- CVSS
- 8.1 (v3.1)
- Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N- Weakness
- CWE-299
- Assigned by
- security-advisories@github.com
Dates
- Published
- 2026-09-04
- Last modified
- 2026-09-08
- Sources
- NVD
References
- https://github.com/forgekeep/nebula-mesh/commit/0426e2f224a9b1e2029029bf923c93ed39d21cdb
- https://github.com/forgekeep/nebula-mesh/releases/tag/v0.7.1
- https://github.com/forgekeep/nebula-mesh/security/advisories/GHSA-cm26-5974-52h8
- https://github.com/forgekeep/nebula-mesh/security/advisories/GHSA-cm26-5974-52h8