CVE-2026-53602 nebula-mesh - Host revocation is not durable: blocked/offboarded hosts can regain a valid certificate
Blocked or offboarded hosts can regain valid certificates because the control plane fails to enforce revocation and operator status during certificate issuance.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-53602?
CVE-2026-53602 is a medium-severity missing authorization vulnerability in forgekeep nebula-mesh, published on 4 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
nebula-mesh is a self-hosted control plane for Slack Nebula mesh VPN. Prior to version 0.3.7, two related authorization gaps let a host that should no longer be trusted obtain a fresh, valid Nebula certificate, because nebula-mgmt does not re-evaluate revocation/authorization state at certificate issuance time — only at poll time. Firstly, the blocklist is not enforced at sign / re-enroll time. internal/api/enroll.go:128 calls caMgr.Sign(...) without consulting the blocklist. The blocklist is only checked in the poll path (internal/api/updates.go:57, fingerprintInBlocklist). The blocklist is keyed by certificate fingerprint (internal/store/sqlite.go), so a re-enrollment produces a new fingerprint that is not in the blocklist. Secondly, renewal does not re-validate operator / CA status. Auto-renewal at poll time (internal/api/updates.go:285-319, signHostCert) reads host.Name, host.Groups, host.NebulaIPs from the DB and re-signs without checking whether the owning operator is still active or the CA still valid. DisableOperator (internal/store/sqlite_operators.go) revokes sessions and API keys but does not retire the operator's CAs, and pki/signer.go checks only CA cert time-expiry, not operator/CA status. This issue has been patched in version 0.3.7.
Which versions are affected by CVE-2026-53602?
3 open source packages ship an affected version, including github.com/forgekeep/nebula-mesh.
| Package | Affected | Fixed in |
|---|---|---|
github.com/forgekeep/nebula-mesh Go | All versions | 0.3.7 |
github.com/forgekeep/nebula-mesh Go | All versions | 0.3.7 |
github.com/forgekeep/nebula-mesh Go | All versions | 0.3.7 |
How do I fix CVE-2026-53602?
Upgrade github.com/forgekeep/nebula-mesh to 0.3.7 or later.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-53602 being exploited?
There is no known exploitation of CVE-2026-53602 in the wild and no public exploit code.
Sources
Also known as GHSA-339v-266x-79xr, GO-2026-5950.