CVE-2026-66798Network attack vector

Code execution via undisclosed use-after-free

Published Aug 28, 2026 · Updated Aug 29, 2026

Use-after-free in Microsoft Edge (Chromium-based) before 152.0.4191.53 allows remote attackers to execute code via web content. Microsoft has not published the affected component, freed object, or invalid operation that processes attacker-controlled content. A user must open the crafted content; the published assessment reports no confidentiality or integrity impact and only a limited service interruption.

CVSS severity4.3
Medium
EPSS probability0.56%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in Microsoft Edge (Chromium-based) before 152.0.4191.53 allows remote attackers to execute code via web content. Microsoft has not published the affected component, freed object, or invalid operation that processes attacker-controlled content. A user must open the crafted content; the published assessment reports no confidentiality or integrity impact and only a limited service interruption.

The record

CVE
CVE-2026-66798
Published
Aug 28, 2026
Updated
Aug 29, 2026
Vendor
Microsoft
Product
Microsoft Edge (Chromium-based)
Classifications
CWE-416, T1203
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 <152.0.4191.53

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft · Microsoft Edge (Chromium-based)version=1.0.0.0 <152.0.4191.53

Published CVSS scores

4.3MicrosoftCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
T1203Exploitation for Client Execution

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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