CVE-2026-55637Public exploitNetwork attack vector

Device-management control via unchecked HTTP origins

Published Aug 25, 2026 · Updated Aug 25, 2026

Origin validation error in GeiserX GenieACS-MCP before 0.3.2 allows remote attackers to control GenieACS operations via DNS rebinding. The Streamable HTTP branch in cmd/server/main.go sends requests directly to the MCP handler without validating attacker-controlled Host or Origin headers. A victim must visit a malicious website while the unauthenticated HTTP transport is running; the site can then read or modify managed-device state.

CVSS severity8.8
High
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Origin validation error in GeiserX GenieACS-MCP before 0.3.2 allows remote attackers to control GenieACS operations via DNS rebinding. The Streamable HTTP branch in cmd/server/main.go sends requests directly to the MCP handler without validating attacker-controlled Host or Origin headers. A victim must visit a malicious website while the unauthenticated HTTP transport is running; the site can then read or modify managed-device state.

The record

CVE
CVE-2026-55637
Published
Aug 25, 2026
Updated
Aug 25, 2026
Vendor
GeiserX
Product
GenieACS-MCP
Classifications
CWE-346, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 25, 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=< 0.3.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

GeiserX · GenieACS-MCPversion=< 0.3.2

Published CVSS scores

8.8GitHubCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:H/SI:H/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.

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 exploitPublished

Weakness, pattern, technique

CWE-346Origin Validation Error
T1189Drive-by Compromise

Public exploit references

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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