CVE-2026-81100Network attack vectorHinoki check available

Browser-driven MCP tool invocation via unchecked Host

Published Aug 27, 2026 · Updated Aug 27, 2026

Origin validation error in Tiger GitHub MCP Server allows remote attackers to invoke MCP tools via browser-based DNS rebinding. src/httpServer.ts calls httpServerFactory without enabling dnsRebindingProtection, so the transport accepts attacker-controlled Host values. Exploitation requires unauthenticated local HTTP mode and a visitor to load an attacker-controlled page; successful requests gain the endpoint's GitHub capabilities.

CVSS severity7.6
High
EPSS probability0.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
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Summary

What happened

Origin validation error in Tiger GitHub MCP Server allows remote attackers to invoke MCP tools via browser-based DNS rebinding. src/httpServer.ts calls httpServerFactory without enabling dnsRebindingProtection, so the transport accepts attacker-controlled Host values. Exploitation requires unauthenticated local HTTP mode and a visitor to load an attacker-controlled page; successful requests gain the endpoint's GitHub capabilities.

The record

CVE
CVE-2026-81100
Published
Aug 27, 2026
Updated
Aug 27, 2026
Vendor
Timescale, Inc.
Product
Tiger GitHub MCP Server
Classifications
CWE-346, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 27, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 27, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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  1. Affected versionversion=0 <e559b57b57cf61277525ec96bbf1edcf01b16a21

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Timescale, Inc. · Tiger GitHub MCP Serverversion=0 <e559b57b57cf61277525ec96bbf1edcf01b16a21

Published CVSS scores

7.6VulnCheckCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-346Origin Validation Error
T1189Drive-by Compromise

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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