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.

Scoring

Severity
HIGH
CVSS base score
8.1
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
EPSS probability
0.25%
CWE
CWE-299, CWE-672
Published
2026-09-04
Last modified
2026-09-08

Affected products

Weakness type

Related vulnerabilities

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