CVE-2026-81099 HIGH

CVE-2026-81099: Timescale tiger-slack DNS Rebinding via Disabled Host Header Allow-List

Vendor Timescale
Product tiger-slack
Weakness CWE-346 · Origin validation
Published August 27, 2026
Last update August 29, 2026

CVSS base score

7.6/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction
Confidentiality
Integrity

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

August 27, 2026 CVE published
August 29, 2026 Record updated