Vulnerability in Timescale Tiger-Slack

CVE-2026-81099

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 v3 metric

CVSS v3 base score 6.8 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N.

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-81099?
CVE-2026-81099 is a medium-severity vulnerability in Timescale Tiger-Slack, classified under Origin Validation Error. CVSS score: 6.8/10. Published 2026-08-27.
How severe is CVE-2026-81099?
Medium severity. CVSS v3 base score is 6.8 out of 10.