CVE-2026-81099

MEDIUMPre-NVD 6.86.8—
EchelonGraph scoreHIGH confidence

Score 6.8 from GitHub Security Advisory (severity: HIGH) published 2026-08-27. the CNA's CVSS baseline 6.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cna:vulncheck, epss, ghsa
Trending — 4 sources updated this week
6.8EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.8Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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
6.8
EG Score
6.8(high)
EG Risk
31(Track)
EG Risk 31/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity68% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
5%
KEV
Not listed

Published

August 27, 2026

Last Modified

August 29, 2026

Advisory Details (3)

Auto-updated Aug 27, 2026
Upstream fix merged — awaiting tagged release. Sources: github_pr.
generic

Timescale tiger-slack DNS Rebinding via Disabled Host Header Allow-List | Advisories | VulnCheck

https://www.vulncheck.com/advisories/timescale-tiger-slack-dns-rebinding-via-disabled-host-header-allow-list
github_pr

Enable DNS rebinding protection for dev + update deps

Fix merged in timescale/tiger-slack PR #146 on 2026-06-26 — awaiting tagged release

https://github.com/timescale/tiger-slack/pull/146
generic

GitHub - timescale/tiger-slack: Real-time Slack ingest and MCP server to power your agentic Slack bots · GitHub

https://github.com/timescale/tiger-slack

Vendor Advisories for CVE-2026-81099(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 13× in last 7d / 13× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-08-30 01:22 UTCEPSS rescore
  2. 2026-08-29 11:59 UTCEG score recompute
  3. 2026-08-29 11:59 UTCGHSA enrichment
  4. 2026-08-28 23:54 UTCEG score recompute
  5. 2026-08-28 23:53 UTCGHSA enrichment
  6. 2026-08-28 21:42 UTCEPSS rescore
  7. 2026-08-27 20:27 UTCEG score recompute
  8. 2026-08-27 20:27 UTCGHSA enrichment
  9. 2026-08-27 20:18 UTCEG score recompute
  10. 2026-08-27 20:18 UTCGHSA enrichment
  11. 2026-08-27 17:27 UTCEG score recompute
  12. 2026-08-27 16:47 UTCEG score recompute
  13. 2026-08-27 16:43 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-81099?
CVE-2026-81099 is a medium vulnerability published on August 27, 2026. 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…
When was CVE-2026-81099 disclosed?
CVE-2026-81099 was first published in the National Vulnerability Database on August 27, 2026, with the most recent update on August 29, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-81099 actively exploited?
CVE-2026-81099 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 94.5% of all scored CVEs.
What is the CVSS score of CVE-2026-81099?
CVE-2026-81099 has a CVSS v4.0 base score of 6.8 (CNA self-assessment; NVD's own analysis pending).
How do I remediate CVE-2026-81099?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-81099, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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