CVE-2023-21720Network attack vector

Browser crash via undisclosed buffer over-read

Published Feb 14, 2023 · Updated Aug 19, 2026

Buffer over-read in Microsoft Edge (Chromium-based) before 109.0.1518.78 allows remote attackers to crash the browser via crafted content. Microsoft identifies an out-of-bounds buffer read but has not published the affected component or malformed-input operation. Exploitation requires user interaction and a high-complexity condition; the documented consequence is a browser service interruption, not data access or modification.

CVSS severity5.3
Medium
EPSS probability1.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Buffer over-read in Microsoft Edge (Chromium-based) before 109.0.1518.78 allows remote attackers to crash the browser via crafted content. Microsoft identifies an out-of-bounds buffer read but has not published the affected component or malformed-input operation. Exploitation requires user interaction and a high-complexity condition; the documented consequence is a browser service interruption, not data access or modification.

The record

CVE
CVE-2023-21720
Published
Feb 14, 2023
Updated
Aug 19, 2026
Vendor
Microsoft
Product
Microsoft Edge (Chromium-based)
Classifications
CWE-126, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 14, 2023CVE publishedPublication date reported by the CVE source.
  2. Aug 19, 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 <109.0.15.18.78

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft · Microsoft Edge (Chromium-based)version=1.0.0 <109.0.15.18.78

Published CVSS scores

5.3Microsoft CorporationCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:H

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-126Buffer Over-read
T1499Endpoint Denial of Service

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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