CVE-2026-81099
Received
Received - Intake
Tiger-Slack MCP HTTP Transport Host Allow-List Bypass
Vulnerability report for CVE-2026-81099, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-08-27
Last updated on: 2026-08-27
Assigner: VulnCheck
Description
Description
tiger-slack started its MCP HTTP transport without enabling the host allow-list the underlying SDK provides. mcp/src/httpServer.ts called the shared httpServerFactory helper and never set the DNS-rebinding-protection option, so the transport accepted a request whatever host it named, and a page in a browser could point a name it controlled at the address the server was bound to and drive the locally reachable Slack MCP server through the visitor's browser. The fix passes the option explicitly alongside a dependency update; the update alone would not have closed it. The repository publishes no release that brackets the fix, so the affected boundary is the commit preceding it.
CVSS Scores
EPSS Scores
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| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| timescale | tiger_slack | to 23faf7ee7e7f73e5ea4f67e627c1aca94bba1f09 (exc) |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-346 | The product does not properly verify that the source of data or communication is valid. |
