Nebula Mesh: Web UI lacks ownership checks, enabling cross-operator access to hosts and networks (read, block, delete)

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

8.8 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS

• CVE-2026-49258: 0.48% estimated exploitation activity in the next 30 days; percentile 41.54 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary The web UI (/ui/) does not apply the per-operator CA scoping the JSON API received for GHSA-598g-h2vc-h5vg. Any authenticated non-admin operator (for example, one created via self-registration or OIDC) can access resources belonging to other operators. Impact A non-admin operator can: - Block or delete any other operator's host. POST /ui/hosts/{id}/block and DELETE /ui/hosts/{id} act on the URL id with no ownership check, so a non-admin can block (revoking the host's certificate via the blocklist) or delete any host in the deployment — a cross-operator denial of service. - Read every operator's hosts and networks. The dashboard, /ui/hosts, the host detail page, /ui/networks (including the create-form error re-render), and the /ui/events stream all return data across all operators, exposing host names, Nebula IPs, public IPs, certificate fingerprints and expiry, and network names and CIDRs. This is the same cross-operator class as GHSA-598g; that remediation covered the JSON…

Published by the source

26 Jun 2026, 21:29 UTC

Last modified by the source

26 Jun 2026, 21:29 UTC

Source last checked

26 Oct 2026, 15:24 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-c6v2-3ffm-vcmc

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# Patch Next advisory brief: CVE-2026-49258

Advisory: Nebula Mesh: Web UI lacks ownership checks, enabling cross-operator access to hosts and networks (read, block, delete)
IDs: CVE-2026-49258, GHSA-c6v2-3ffm-vcmc
Record: https://patchnext.com/advisories/cve-2026-49258 (revision 1, source checked 26 Oct 2026, 15:24 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/juev/nebula-mesh: affected <= 0.3.4

## Suggested inspection (read-only)
- Go github.com/juev/nebula-mesh: check the installed version with your package manager.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/juev/nebula-mesh.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-c6v2-3ffm-vcmc (GitHub-reviewed advisory GHSA-c6v2-3ffm-vcmc lists affected ranges: Go github.com/juev/nebula-mesh >=0 <=0.3.4)

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