Vulnerability · Published Sep 4, 2026 · Assigned by GitHub_M
CVE-2026-55512nebula-mesh: Unauthenticated OIDC login endpoint allocates unbounded in-memory state entries without rate limiting
Medium 5.3
In plain English
A medium-severity uncontrolled resource consumption in nebula-mesh from forgekeep. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 49% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
nebula-mesh is a self-hosted control plane for Slack Nebula mesh VPN. From version 0.2.0 to before version 0.5.0, when OIDC is enabled, GET /ui/oidc/login is reachable without authentication and is registered outside the Web UI rate-limited auth routes. Every request creates a fresh random OIDC state value and stores it in an in-memory map for 10m. Expired states are swept lazily, but there is no rate limit or maximum live-state cap on the allocation path. An unauthenticated remote client can therefore grow OIDC.states for the full state TTL, bounded by request throughput rather than by configured auth rate limits. This issue has been patched in version 0.5.0.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Go | github.com/forgekeep/nebula-mesh | 0.5.0 | GHSA-m3cx-mwpg-32jg |
| Go | github.com/forgekeep/nebula-mesh | 0.5.0 | GO-2026-5989 |
| Go | github.com/juev/nebula-mesh | no fix listed | GO-2026-5989 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| forgekeep | nebula-mesh | >= 0.2.0, < 0.5.0 |
Weakness: CWE-400 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L