CVE-2026-81099 timescale CVE debrief

Who should care

Defenders responsible for the tiger-slack project and its dependencies should assess exposure and apply the fix to prevent DNS rebinding attacks. Defenders should verify the affected versions and apply the fix to prevent DNS rebinding attacks. The vulnerability allows for DNS rebinding attacks, which could lead to unauthorized access.

Why it matters

CVE-2026-81099 is a DNS rebinding vulnerability in the tiger-slack project that allows for unauthorized access. Defenders should prioritize verifying the affected versions and applying the fix.

• Defenders should verify the affected versions and apply the fix to prevent DNS rebinding attacks
• The vulnerability allows for DNS rebinding attacks, which could lead to unauthorized access

Technical summary

The tiger-slack project started its MCP HTTP transport without enabling the host allow-list provided by the underlying SDK. The mcp/src/httpServer.ts file called the shared httpServerFactory helper and never set the DNS-rebinding-protection option, allowing requests from any host. 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.

Defensive priority

Defenders should prioritize verifying the affected versions and applying the fix, as the vulnerability allows for DNS rebinding attacks.

Recommended defensive actions

• Verify the affected versions of the tiger-slack project
• Apply the fix by passing the DNS-rebinding-protection option explicitly
• Review the dependency update and ensure it is applied
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, but the affected versions and scope of impact require further verification. The tiger-slack project started its MCP HTTP transport without enabling the host allow-list provided by the underlying SDK. The mcp/src/httpServer.ts file called the shared httpServerFactory helper and never set the DNS-rebinding-protection option, allowing requests from any host. A page in a browser could point a name it controlled at the address the server was bound to and drive the locally

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.