CVE-2021-30563Known exploitationNetwork attack vector

Heap corruption via V8 type confusion

Published Aug 3, 2021 · Updated Oct 21, 2025

Type confusion in V8 in Google Chrome before 91.0.4472.164 allows remote attackers to corrupt heap memory through a crafted HTML page. Google identifies the V8 engine and type-confusion behavior but does not disclose the affected code locus or incompatible-type operation. Exploitation requires a user to open attacker-controlled web content; successful heap corruption compromises browser confidentiality, integrity, and availability.

CVSS severity8.8
High
EPSS probability8.93%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Type confusion in V8 in Google Chrome before 91.0.4472.164 allows remote attackers to corrupt heap memory through a crafted HTML page. Google identifies the V8 engine and type-confusion behavior but does not disclose the affected code locus or incompatible-type operation. Exploitation requires a user to open attacker-controlled web content; successful heap corruption compromises browser confidentiality, integrity, and availability.

The record

CVE
CVE-2021-30563
Published
Aug 3, 2021
Updated
Oct 21, 2025
Vendor
Google Cloud
Product
Google Chrome
Classifications
CWE-843, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 3, 2021CVE publishedPublication date reported by the CVE source.
  2. Nov 3, 2021Exploitation reportedCISA Known Exploited Vulnerabilities listing
  3. Oct 21, 2025Record 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=unspecified <91.0.4472.164

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Google Cloud · Google Chromeversion=unspecified <91.0.4472.164

Published CVSS scores

8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
6.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/A:P
8.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/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 exploitationReported
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-843Access of Resource Using Incompatible Type ('Type Confusion')
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.

Reported exploitation

Technologies

Your stack

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Your stack

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