CVE-2026-55512Medium· 5.3▾ TwilightPoC available

nebula-mesh is a self-hosted control plane for Slack Nebula mesh VPN

▾ Twilight zone — High severity, or a signal on a lesser flaw

Depth score41/ 100 · Moderate

impact 29.2 · likelihood 0.1 · exploitation 12

⚡ Agent-ready:Raw markdown ↗JSON ↗

Proof of concept

A public proof-of-concept already exists for this vulnerability — see Exploit availability below.

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Published

Sep 4, 2026

Updated

Sep 9, 2026

CVSS

5.3

Vendor

forgekeep

Product

nebula-mesh

CWE

CWE-400

Depth score

41 · Moderate

EPSS

0.33% · p27

Platforms

—

Source

NVD

Vector

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

CISA SSVC

decided 2026-09-09

Exploitation: poc
Automatable: yes
Technical impact: partial

Stakeholder-Specific Vulnerability Categorization from CISA's ADP record at CVE.org: whether exploitation is observed, whether an attack can be automated, and how much of the system is at stake.

EPSS history

Exploit-prediction probability, daily snapshots since Sep 5.

0.3% → 0.3%

Timeline

Disclosure to exploitation, from the record and what we observed since indexing it.

4 events · 10 days

Sep 4, 2026Published
Disclosed via NVD
Sep 5, 2026EPSS first tracked
0.3%
Sep 9, 2026Record revised
Last analysed / modified upstream
Sep 14, 2026Public exploit observed
Exploit / PoC code exists

forgekeep CWE-400 #nvd #cve.org #exploit-available #ghsa #go

Affected

nebula-mesh >= 0.2.0, < 0.5.0

Patched in

github.com/forgekeep/nebula-mesh 0.5.0

Full technical detail▾

Overview

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.

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

Package advisory (CVE-2026-55512)

Affected packages:

github.com/forgekeep/nebula-mesh >= 0.2.0, < 0.5.0

Patched in:

github.com/forgekeep/nebula-mesh 0.5.0

Source: https://github.com/advisories/GHSA-m3cx-mwpg-32jg

References

Change history

Field changes observed since this record was first indexed.

Sep 14, 2026Public exploit / PoC published
Sep 14, 2026Public exploit flag cleared
Sep 14, 2026Public exploit / PoC published
Sep 14, 2026Public exploit flag cleared
Sep 14, 2026Public exploit / PoC published
Sep 14, 2026Public exploit flag cleared
Sep 14, 2026Public exploit / PoC published
Sep 14, 2026Public exploit flag cleared
Sep 14, 2026Public exploit / PoC published
Sep 14, 2026Public exploit flag cleared
Sep 14, 2026Public exploit / PoC published
Sep 14, 2026Public exploit flag cleared

Related vulnerabilities

Connected by shared product, vendor, weakness, or advisory.

#nvd#cve.org#exploit-available#ghsa#go

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