CVE-2026-55512
Received Received - Intake

Memory Exhaustion via Unauthenticated OIDC State in Nebula-Mesh

Publication date: 2026-09-04

Last updated on: 2026-09-04

Assigner: GitHub, Inc.

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.

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Meta Information

Published
2026-09-04
Last Modified
2026-09-04
Generated
2026-09-05
AI Q&A
2026-09-04
EPSS Evaluated
N/A
NVD
CVE-2026-55512

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
nebula-mesh nebula_mesh From 0.2.0 (inc) to 0.5.0 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-400 The product does not properly control the allocation and maintenance of a limited resource.

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Executive Summary

This vulnerability affects nebula-mesh, a control plane for Slack Nebula mesh VPN. When OIDC authentication is enabled, an unauthenticated attacker can repeatedly access the GET /ui/oidc/login endpoint. This endpoint generates and stores random OIDC state values in memory for up to 10 minutes without rate limiting. The issue allows attackers to consume excessive memory by creating many state values, potentially leading to denial of service.

Impact Analysis

If you use nebula-mesh with OIDC enabled, an attacker could exploit this to overload the server by consuming memory with fake OIDC state values. This may cause the service to slow down or crash, disrupting VPN operations. The vulnerability does not allow data theft or privilege escalation but can impact availability.

Compliance Impact

This vulnerability primarily impacts availability and could lead to service disruptions. While it does not directly violate GDPR or HIPAA, repeated outages may affect compliance with availability requirements. Organizations should patch to maintain service reliability and meet operational standards.

Mitigation Strategies

Upgrade nebula-mesh to version 0.5.0 or later to patch the vulnerability. Disable OIDC if not required or restrict access to the GET /ui/oidc/login endpoint.

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