# CVE-2026-53603: nebula-mesh: Operator session tokens stored in plaintext in the database

> Attackers with database access can steal plaintext operator session tokens to hijack admin sessions in nebula-mesh.

- **Severity:** High 7.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA: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-q4vm-pq3q-8wgq, GO-2026-5991

## What is CVE-2026-53603?

CVE-2026-53603 is a high-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. Prior to version 0.3.8, Operator session tokens are stored in plaintext in the operator_sessions table (the token column is the PRIMARY KEY). The session token is a 32-byte random hex value sent directly in a cookie and valid for 24 hours. Anyone who can read the database (backup, snapshot, file copy, or SQL-level disclosure) obtains every active session token and can hijack operator sessions directly, with no further authentication. This issue has been patched in version 0.3.8.

Weakness: CWE-522 (Insufficiently Protected Credentials), CWE-312 (Cleartext Storage of Sensitive Information)

## Which versions are affected by CVE-2026-53603?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/forgekeep/nebula-mesh` | Go | All versions | 0.3.8 |
| `github.com/forgekeep/nebula-mesh` | Go | All versions | 0.3.8 |
| `github.com/forgekeep/nebula-mesh` | Go | All versions | 0.3.8 |

## How do I fix CVE-2026-53603?

Upgrade github.com/forgekeep/nebula-mesh to 0.3.8 or later.

## Is CVE-2026-53603 being exploited?

There is no known exploitation of CVE-2026-53603 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-53603 and fix it if it is affected.

What it is: CVE-2026-53603 is a high-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: There is no known exploitation of CVE-2026-53603 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/forgekeep/nebula-mesh (Go): affected all versions; fixed in 0.3.8
- github.com/forgekeep/nebula-mesh (Go): affected all versions; fixed in 0.3.8
- github.com/forgekeep/nebula-mesh (Go): affected all versions; fixed in 0.3.8

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-2026-53603/ (Markdown: https://insights.sbomify.com/CVE-2026-53603/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-53603
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-53603
- OSV: https://osv.dev/vulnerability/CVE-2026-53603

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-53603/
Summaries are generated and may contain mistakes; the official description above is the record.