CVE-2026-70309Network attack vector

Security boundary bypass via origin validation error

Published Aug 28, 2026 · Updated Aug 29, 2026

Origin validation error in Microsoft Edge (Chromium-based) before 150.0.4078.65 allows remote attackers to bypass a security boundary. Microsoft has not disclosed which Edge component accepts an untrusted origin or how that origin is validated incorrectly. Exploitation requires user interaction and can expose or alter limited data, while no service interruption is reported.

CVSS severity5.4
Medium
EPSS probability0.16%
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 Microsoft Edge (Chromium-based) before 150.0.4078.65 allows remote attackers to bypass a security boundary. Microsoft has not disclosed which Edge component accepts an untrusted origin or how that origin is validated incorrectly. Exploitation requires user interaction and can expose or alter limited data, while no service interruption is reported.

The record

CVE
CVE-2026-70309
Published
Aug 28, 2026
Updated
Aug 29, 2026
Vendor
Microsoft
Product
Microsoft Edge (Chromium-based)
Classifications
CWE-346
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 28, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 29, 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=1.0.0.0 <150.0.4078.65

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft · Microsoft Edge (Chromium-based)version=1.0.0.0 <150.0.4078.65

Published CVSS scores

5.4MicrosoftCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/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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