CVE-2021-37993Network attack vector

Heap corruption via PDF Accessibility use-after-free

Published Nov 2, 2021 · Updated Aug 4, 2024

Use after free in Google Chrome PDF Accessibility before 95.0.4638.54 allows remote attackers to corrupt heap memory via crafted HTML. Public records identify the PDF Accessibility component but do not disclose the freed object or the incorrect lifetime operation. Exploitation requires a user to load attacker-controlled HTML, and the published consequence is heap corruption within the browser process.

CVSS severity8.8
High
EPSS probability0.85%
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 PDF Accessibility before 95.0.4638.54 allows remote attackers to corrupt heap memory via crafted HTML. Public records identify the PDF Accessibility component but do not disclose the freed object or the incorrect lifetime operation. Exploitation requires a user to load attacker-controlled HTML, and the published consequence is heap corruption within the browser process.

The record

CVE
CVE-2021-37993
Published
Nov 2, 2021
Updated
Aug 4, 2024
Vendor
Google Cloud
Product
Google Chrome
Classifications
CWE-416, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 2, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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 <95.0.4638.54

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Google Cloud · Google Chromeversion=unspecified <95.0.4638.54

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

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-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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