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.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
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
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.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-108586 being exploited?
There is no known exploitation of CVE-2026-108586 in the wild and no public exploit code.
Sources
Also known as GHSA-w2j7-xxh9-9q67.