CVE-2026-47724: nebula-mesh: API endpoints lack ownership checks, enabling cross-operator privilege escalation

Should you act?

Critical, preconditions apply

Severe if exploited, but exploitation needs conditions that may not apply to you. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
• EPSS 0.5%, percentile 40: FIRST’s model estimates a 0.5% chance of exploitation activity in the next 30 days, higher than 40% of all scored CVEs (low). EPSS is a probability, not a verdict.
• Needs an account (low (any account)). Exposure depends on who can log in.
• Only applies if your dependency tree includes github.com/juev/nebula-mesh (Go) < 0.3.4, fixed in 0.3.4. Check your lockfile, including transitive dependencies.

What it is

nebula-mesh is a self-hosted control plane for Slack Nebula mesh virtual private network. Prior to version 0.3.4, the /api/v1/ route surface trusts the bearer token alone for authorisation on most endpoints. The codebase itself admits this at internal/api/hosts.go:384: "API trusts the bearer token for authorisation; per-CA ownership is enforced only in the Web layer." The Web UI gates state-changing routes through loadAccessibleCA (internal/web/cas.go); CA-management endpoints in internal/api/cas.go ALSO have proper canAccessCA gates. The gap is on the host, network, firewall, mobile-bundle, and most operator endpoints. Combined with the per-operator CA model from ADR 0002, this gives any non-admin operator API key broad cross-tenant access — instant privilege escalation in the worst case. Version 0.3.4 fixes the issue.

From the GitHub advisory

The /api/v1/ route surface trusts the bearer token alone for authorisation on most endpoints. The codebase itself admits this at internal/api/hosts.go:384: "API trusts the bearer token for authorisation; per-CA ownership is enforced only in the Web layer."

The Web UI gates state-changing routes through loadAccessibleCA (internal/web/cas.go); CA-management endpoints in internal/api/cas.go ALSO have proper canAccessCA gates. The gap is on the host, network, firewall, mobile-bundle, and most operator endpoints. Combined with the per-operator CA model from ADR 0002, this gives any non-admin operator API key broad cross-tenant access — instant privilege escalation in the worst case.

Affected All released versions prior to v0.3.4.

Exploit chain

A) Mint admin API key from any operator key (instant privilege escalation) internal/api/operators.go:118 — handleCreateOperatorAPIKey does no admin check and no actor/target-operator ownership check. Any operator key can call it for any operator (including admins) and receive a fresh bearer.

Weakness type: CWE-862.

Product: github.com/juev/nebula-mesh (Go) · Assigned by: GitHub_M · Published: 2026-07-23

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: low (any account)
• User interaction: none
• Scope: changed (can affect other components)

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation none, automatable no, technical impact total.
• FIRST EPSS (model of 2026-10-21): 0.48% probability of exploitation activity in the next 30 days; percentile 40.

Timeline

• 2026-06-08 — GitHub-reviewed advisory GHSA-598g-h2vc-h5vg published (critical)
• 2026-07-23 — CVE record published by GitHub_M
• 2026-07-28 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-598g-h2vc-h5vg github.com
2. CVE.org record CVE-2026-47724 cve.org
3. NVD entry CVE-2026-47724 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. github.com github.com

Critical Go advisories · Today’s Security Digest