forgekeep nebula-mesh up to 0.3.5 Web UI improper authentication

Summaryinfo

A vulnerability was found in forgekeep nebula-mesh up to 0.3.5. It has been rated as very critical. Impacted is an unknown function of the component Web UI. This manipulation causes improper authentication. This vulnerability is handled as CVE-2026-49258. The attack can be initiated remotely. There is not any exploit available.

Detailsinfo

A vulnerability has been found in forgekeep nebula-mesh up to 0.3.5 and classified as very critical. Affected by this vulnerability is an unknown function of the component Web UI. The manipulation with an unknown input leads to a improper authentication vulnerability. The CWE definition for the vulnerability is CWE-287. When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

Nebula Mesh is a self-hosted control plane for the Slack Nebula mesh VPN. In versions 0.3.5 and below, the web UI (/ui/*) does not apply the per-operator CA scoping employed by the JSON API. This was partially addressed by GHSA-598g-h2vc-h5vg, but the changes were not implemented in the web read/mutation surface. Any authenticated non-admin operator (for example, one created via self-registration or OIDC) can access resources belonging to other operators. The host create/edit/mobile-bundle/network-create paths and all CA-management routes were already correctly scoped. A malicious operator could block or delete any other operator's host, or read any operator's hosts and networks. This issue has been fixed in version 0.3.6.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-49258 since 05/28/2026. The exploitation appears to be easy. The attack can be launched remotely. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 07/28/2026).

Upgrading to version 0.3.6 eliminates this vulnerability.

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Productinfo

Vendor

• forgekeep

Name

• nebula-mesh

Version

• 0.3.0
• 0.3.1
• 0.3.2
• 0.3.3
• 0.3.4
• 0.3.5

Website

• Product: https://github.com/forgekeep/nebula-mesh/

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