CVE-2021-21148Known exploitationPublic exploitNetwork attack vector

Heap corruption via crafted HTML in V8

Published Feb 9, 2021 · Updated Oct 21, 2025

Heap buffer overflow in Google Chrome before 88.0.4324.150 allows remote attackers to corrupt V8 heap memory through a crafted HTML page. Google identifies V8 as the affected component but does not disclose the function, buffer, or bounds-checking operation that fails. A user must load attacker-controlled content, and Google reports that an exploit was used in the wild.

CVSS severity8.8
High
EPSS probability19.97%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap buffer overflow in Google Chrome before 88.0.4324.150 allows remote attackers to corrupt V8 heap memory through a crafted HTML page. Google identifies V8 as the affected component but does not disclose the function, buffer, or bounds-checking operation that fails. A user must load attacker-controlled content, and Google reports that an exploit was used in the wild.

The record

CVE
CVE-2021-21148
Published
Feb 9, 2021
Updated
Oct 21, 2025
Vendor
Google Cloud
Product
Google Chrome
Classifications
CWE-787, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 9, 2021CVE publishedPublication date reported by the CVE source.
  2. Oct 21, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <88.0.4324.150

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Google Cloud · Google Chromeversion=unspecified <88.0.4324.150

Published CVSS scores

6.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/A:P
8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationReported
Public exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1203Exploitation for Client Execution

Public exploit references

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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