CVE-2021-21124Network attack vector

Sandbox escape via Speech Recognizer use-after-free

Published Feb 9, 2021 · Updated Aug 3, 2024

Use-after-free in Google Chrome on Android before 88.0.4324.96 allows remote attackers to escape the sandbox via crafted HTML. Google identifies Speech Recognizer as the locus but has not published which object is freed or which later operation reuses it. Exploitation requires Chrome to process attacker-controlled HTML, and successful object reuse crosses the browser sandbox boundary.

CVSS severityUnavailable
Unscored
EPSS probability7.85%
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 Google Chrome on Android before 88.0.4324.96 allows remote attackers to escape the sandbox via crafted HTML. Google identifies Speech Recognizer as the locus but has not published which object is freed or which later operation reuses it. Exploitation requires Chrome to process attacker-controlled HTML, and successful object reuse crosses the browser sandbox boundary.

The record

CVE
CVE-2021-21124
Published
Feb 9, 2021
Updated
Aug 3, 2024
Vendor
Google Cloud
Product
Google Chrome
Classifications
CWE-416, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 9, 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 <88.0.4324.96

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Google Cloud · Google Chromeversion=unspecified <88.0.4324.96

Published CVSS scores

No CVSS assessment is available in this record.

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.

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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-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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