CVE-2026-17854Network attack vector

Same-origin policy bypass via WebMCP policy failure

Published Jul 30, 2026 · Updated Jul 30, 2026

Origin validation error in WebMCP in Google Chrome before 151.0.7922.72 allows remote attackers to bypass the same-origin policy. Google's public advisory identifies insufficient WebMCP policy enforcement but does not disclose the specific policy check or code path that mishandles a crafted HTML page. A victim must load the crafted page, enabling unauthorized cross-origin modification without reported data disclosure or service interruption.

CVSS severity6.5
Medium
EPSS probability0.19%
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 WebMCP in Google Chrome before 151.0.7922.72 allows remote attackers to bypass the same-origin policy. Google's public advisory identifies insufficient WebMCP policy enforcement but does not disclose the specific policy check or code path that mishandles a crafted HTML page. A victim must load the crafted page, enabling unauthorized cross-origin modification without reported data disclosure or service interruption.

The record

CVE
CVE-2026-17854
Published
Jul 30, 2026
Updated
Jul 30, 2026
Vendor
Go standard library
Product
Google Chrome
Classifications
CWE-346
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 30, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 30, 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=151.0.7922.72 <151.0.7922.72

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Go standard library · Google Chromeversion=151.0.7922.72 <151.0.7922.72

Published CVSS scores

6.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/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

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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