Medium severity5.4NVD Advisory· Published Oct 10, 2026
CVE-2026-108586
CVE-2026-108586
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 to list and invoke tools on backend MCP servers outside their granted scopes.
Affected products
1- Range: 0.20.0-0.39.0
Patches
Vulnerability mechanics
References
4- github.com/1mcp-app/agent/blob/v0.39.0/src/sdk/legacy/transport/http/middlewares/scopeAuthMiddleware.tsnvd
- github.com/1mcp-app/agent/blob/v0.39.0/src/transport/http/routes/inspectHelpers.tsnvd
- hackmd.io/@haind/1mcp-negated-tag-filter-oauth-scope-bypassnvd
- www.vulncheck.com/advisories/1mcp-agent-0.20.0-through-0.39.0-oauth-tag-scope-bypass-via-negated-tag-filternvd
News mentions
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