Description
nebula-mesh is a self-hosted control plane for Slack Nebula mesh virtual private network. Prior to version 0.3.3, every /ui/* POST / PUT / PATCH / DELETE route processes the request as soon as the session cookie validates. SameSite=Lax on the session cookie prevents most cross-site form submits but does not protect: top-level form-submit navigations from third-party pages (some browsers still send Lax cookies on top-level POSTs); same-registrable-domain attackers (sibling-subdomain XSS, subdomain takeover); the GET /ui/logout route, which a third-party <img src=".../ui/logout"> can force-trigger. This issue has been patched in version 0.3.3.
References3
Metrics
- CVSS 4.0
-
6.9
MEDIUM
Score source: CNA
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - EPSS — exploit probability
- 0% percentile: 8 · as of 13 November 2026
- CWE
- CWE-352
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.