# CVE-2026-55176: Soft Machine: Cross-tenant workspace API auth bypass via shared `CONTAINER_SHARED_SECRET` bearer token

> Attackers can bypass authentication using a shared secret to access and modify other tenants' workspaces in the Soft Machine cloud environment.

- **Severity:** Critical 9.0 (`CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 30 Sep 2026
- **Updated:** 2 Oct 2026

## What is CVE-2026-55176?

CVE-2026-55176 is a critical authentication bypass vulnerability in Soft-Machine-io security, published on 30 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Soft Machine is a Virtual Machine–based agentic development environment / Cloud OS. In versions 0.2.247 and prior, two authentication helpers in /app/server.js — verifyContainerAuth() and authenticateWorkspaceHttp() — accept the global CONTAINER_SHARED_SECRET as a bearer token without verifying which workspace the caller belongs to. Because that secret is set identically on every container in the Fly app and is reachable from the user-facing process environment inside each workspace, any tenant can use it to authenticate to any other tenant's workspace API. The result is cross-workspace read, write, and destructive-restore primitives reachable from any paying customer's shell. The existing per-workspace token check (workspaceTokenMatches) protects the user-facing per-workspace token path, but the shared-secret bearer path bypasses it entirely. At time of publication, there are no publicly known patches.

Weakness: CWE-863 (Incorrect Authorization)

## Which versions are affected by CVE-2026-55176?


## How do I fix CVE-2026-55176?

No fix has been published for CVE-2026-55176 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-55176 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55176 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-55176 and fix it if it is affected.

What it is: CVE-2026-55176 is a critical authentication bypass vulnerability in Soft-Machine-io security, published on 30 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55176 exists.

Affected product: Soft-Machine-io security. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-55176/ (Markdown: https://insights.sbomify.com/CVE-2026-55176/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-55176
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-55176
- OSV: https://osv.dev/vulnerability/CVE-2026-55176

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-55176/
Summaries are generated and may contain mistakes; the official description above is the record.