CVE-2021-21154Network attack vector

Sandbox escape via Tab Strip heap overflow

Published Feb 22, 2021 · Updated Aug 3, 2024

Heap buffer overflow in Google Chrome before 88.0.4324.182 allows remote attackers to escape the browser sandbox via crafted HTML. Google identifies the locus only as Tab Strip and has not published the affected function, buffer operation, or triggering input structure. Exploitation requires user interaction with the crafted page and prior compromise of Chrome's renderer process, after which the attacker can cross the renderer sandbox boundary.

CVSS severity9.6
Critical
EPSS probability1.42%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap buffer overflow in Google Chrome before 88.0.4324.182 allows remote attackers to escape the browser sandbox via crafted HTML. Google identifies the locus only as Tab Strip and has not published the affected function, buffer operation, or triggering input structure. Exploitation requires user interaction with the crafted page and prior compromise of Chrome's renderer process, after which the attacker can cross the renderer sandbox boundary.

The record

CVE
CVE-2021-21154
Published
Feb 22, 2021
Updated
Aug 3, 2024
Vendor
Google Cloud
Product
Google Chrome
Classifications
CWE-787, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 22, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record 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 <88.0.4324.182

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Google Cloud · Google Chromeversion=unspecified <88.0.4324.182

Published CVSS scores

9.6NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
6.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/A:P

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-787Out-of-bounds Write
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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