# CVE-2026-108586: 1MCP Agent 0.20.0 through 0.39.0 OAuth Tag-Scope Bypass via Negated Tag Filter

> Authenticated attackers can bypass OAuth tag-scope restrictions to access unauthorized tools and data in 1MCP Agent.

- **Severity:** Medium 5.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/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:** No
- **Published:** 10 Oct 2026
- **Updated:** 13 Oct 2026
- **Also known as:** GHSA-w2j7-xxh9-9q67

## What is CVE-2026-108586?

CVE-2026-108586 is a medium-severity authentication bypass vulnerability in 1mcp-app @1mcp/agent, published on 10 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

1MCP Agent (@1mcp/agent) 0.20.0 through 0.39.0 contains an incorrect authorization vulnerability that allows authenticated clients to bypass OAuth tag-scope enforcement using negated advanced tag-filter expressions. Attackers holding a single-tag token can send a filter like not <granted-tag> to list and invoke tools on backend MCP servers outside their granted scopes.

Weakness: CWE-863 (Incorrect Authorization)

## Which versions are affected by CVE-2026-108586?


## How do I fix CVE-2026-108586?

No fix has been published for CVE-2026-108586 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-108586 being exploited?

There is no known exploitation of CVE-2026-108586 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-108586 and fix it if it is affected.

What it is: CVE-2026-108586 is a medium-severity authentication bypass vulnerability in 1mcp-app @1mcp/agent, published on 10 Oct 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-2026-108586 in the wild and no public exploit code.

Affected product: 1mcp-app @1mcp/agent. 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-2026-108586/ (Markdown: https://insights.sbomify.com/CVE-2026-108586/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-108586
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-108586
- OSV: https://osv.dev/vulnerability/CVE-2026-108586

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-108586/
Summaries are generated and may contain mistakes; the official description above is the record.