CVE-2026-35577Network attack vector

Unauthorized tool invocation via unvalidated Host header

Published Apr 9, 2026 · Updated Apr 9, 2026

Origin validation failure in Apollo MCP Server before 1.7.0 allows remote attackers to invoke MCP tools through DNS rebinding. The StreamableHTTP request path accepted attacker-controlled Host headers without checking expected localhost names and ports. Exploitation requires a local HTTP deployment without authentication or network controls and a user visiting a malicious site; stdio transport is unaffected.

CVSS severity8.1
High
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Origin validation failure in Apollo MCP Server before 1.7.0 allows remote attackers to invoke MCP tools through DNS rebinding. The StreamableHTTP request path accepted attacker-controlled Host headers without checking expected localhost names and ports. Exploitation requires a local HTTP deployment without authentication or network controls and a user visiting a malicious site; stdio transport is unaffected.

The record

CVE
CVE-2026-35577
Published
Apr 9, 2026
Updated
Apr 9, 2026
Vendor
Apollo GraphQL
Product
Apollo MCP Server
Classifications
CWE-346, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 9, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 9, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 1.7.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Apollo GraphQL · Apollo MCP Serverversion=< 1.7.0

Published CVSS scores

6.8GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N
8.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A: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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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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