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CVE-2026-53602 — nebula-mesh

CVE-2026-53602 is a CWE-285 vulnerability in github.com/forgekeep/nebula-mesh. A fix is available for github.com/forgekeep/nebula-mesh — see the affected versions and patch details below.

nebula-mesh - Host revocation is not durable: blocked/offboarded hosts can regain a valid certificate

Also known asGHSA-339v-266x-79xrGO-2026-5950
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Oct 11, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-53602.

EPSS Exploitation Probability

via FIRST.org ↗
0.3%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs22th percentile — riskier than 22% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected
🐹github.com/forgekeep/nebula-mesh

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

Summary

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.

1. Blocklist 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.

mintEnrollmentTokenForHost (internal/api/hosts.go:491) authorizes the caller via canAccessHost but does not check the host status. There is no guard preventing a blocked host from transitioning back to enrolled (internal/store/sqlite.go, enrollHostInTx updates status unconditionally).

Impact: A host that an operator has blocked can be silently un-blocked by issuing a new enrollment token and re-enrolling — it receives a fresh certificate (new fingerprint) that passes all subsequent poll-time blocklist checks. Revocation is therefore not durable. Requires an operator action (minting a re-enroll token), so this is an integrity/operational-revocation failure rather than an unauthenticated bypass.

2. 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.

Impact: A host enrolled under an operator who is later disabled continues to renew its certificate indefinitely. Offboarding an operator does not cut off the hosts they provisioned.

Affected versions

Latest tagged release (v0.3.6) and main.

Remediation

  1. Call a blocklist/status guard inside handleEnroll and signHostCert before caMgr.Sign(...); refuse issuance for a host whose status is blocked or whose previous fingerprint is on the blocklist. Require an explicit unblock before re-enroll.
  2. At renewal, re-resolve the owning operator/CA status and reject renewal if the operator is disabled or the CA retired (force re-enrollment instead).

Discovery

Found during an internal source + offensive security audit (tracking issue #178). Adversarially cross-verified against the code paths above.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐹Gogithub.com/forgekeep/nebula-meshall versions0.3.7go get github.com/forgekeep/nebula-mesh@v0.3.7

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/forgekeep/nebula-mesh, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update github.com/forgekeep/nebula-mesh to 0.3.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-53602 is resolved across your whole dependency graph.

  3. Workarounds

    Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Frequently Asked Questions

## Summary 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. ## 1. Blocklist 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-enrollmen
O3 Security · Impact-Aware SCA

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CVE-2026-53602: nebula-mesh — Fixed in 0.3.7