# CVE-2026-55513: nebula-mesh: Web UI host creation ignores configured enrollment token TTL and mints 24-hour bearer enrollment tokens

> Authenticated operators can bypass configured enrollment token TTL limits via the Web UI, minting tokens valid for 24 hours instead of the intended shorter duration.

- **Severity:** Medium 5.4 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 4 Sep 2026
- **Updated:** 8 Sep 2026
- **Also known as:** GHSA-g4x6-jcvr-9m3g, GO-2026-5987

## What is CVE-2026-55513?

CVE-2026-55513 is a medium-severity vulnerability in forgekeep nebula-mesh, published on 4 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

nebula-mesh is a self-hosted control plane for Slack Nebula mesh VPN. From version 0.3.0 to before version 0.5.0, the nebula-mgmt Web UI host-creation path ignores both the server-wide enrollment_token_ttl security setting and per-network network_config.enrollment_token_ttl overrides. API host creation and token-regeneration paths use the configured TTL resolver, but POST /ui/hosts hardcodes now.Add(24 * time.Hour) for newly minted agent enrollment tokens. In deployments that intentionally reduce enrollment-token lifetime, any authenticated operator who can create a host through the Web UI can still mint a bearer enrollment token valid for about 24 hours. This issue has been patched in version 0.5.0.

Weakness: CWE-613 (DEPRECATED: Insufficient Session Expiration)

## Which versions are affected by CVE-2026-55513?

4 open source packages ship an affected version, including github.com/forgekeep/nebula-mesh and github.com/juev/nebula-mesh.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/forgekeep/nebula-mesh` | Go | From 0.3.0 | 0.5.0 |
| `github.com/forgekeep/nebula-mesh` | Go | From 0.3.0 | 0.5.0 |
| `github.com/forgekeep/nebula-mesh` | Go | From 0.4.0 | 0.5.0 |
| `github.com/juev/nebula-mesh` | Go | From 0.3.0 | None |

## How do I fix CVE-2026-55513?

Upgrade github.com/forgekeep/nebula-mesh to 0.5.0 or later.

## Is CVE-2026-55513 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55513 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-55513 and fix it if it is affected.

What it is: CVE-2026-55513 is a medium-severity vulnerability in forgekeep nebula-mesh, published on 4 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55513 exists.

Affected packages and fixed versions:
- github.com/forgekeep/nebula-mesh (Go): affected from 0.3.0; fixed in 0.5.0
- github.com/forgekeep/nebula-mesh (Go): affected from 0.3.0; fixed in 0.5.0
- github.com/forgekeep/nebula-mesh (Go): affected from 0.4.0; fixed in 0.5.0
- github.com/juev/nebula-mesh (Go): affected from 0.3.0; no fix listed

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-55513/ (Markdown: https://insights.sbomify.com/CVE-2026-55513/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-55513
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-55513
- OSV: https://osv.dev/vulnerability/CVE-2026-55513

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-55513/
Summaries are generated and may contain mistakes; the official description above is the record.