CVE-2021-21172Network attack vector

Filesystem restriction bypass via accepted shortcut filenames

Published Mar 9, 2021 · Updated Aug 3, 2024

Insufficient policy enforcement in Google Chrome before 89.0.4389.72 on Windows allows remote attackers to bypass filesystem restrictions via HTML. The File System Access API getFileHandle() method accepts .lnk filenames instead of blocking the Windows shortcut type. A user must open the crafted page and grant directory access; the page can then create a Windows shortcut in the selected directory.

CVSS severity8.1
High
EPSS probability1.65%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Insufficient policy enforcement in Google Chrome before 89.0.4389.72 on Windows allows remote attackers to bypass filesystem restrictions via HTML. The File System Access API getFileHandle() method accepts .lnk filenames instead of blocking the Windows shortcut type. A user must open the crafted page and grant directory access; the page can then create a Windows shortcut in the selected directory.

The record

CVE
CVE-2021-21172
Published
Mar 9, 2021
Updated
Aug 3, 2024
Vendor
Google Cloud
Product
Google Chrome
Classifications
T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 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 <89.0.4389.72

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Google Cloud · Google Chromeversion=unspecified <89.0.4389.72

Published CVSS scores

8.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
5.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/A:N

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

T1189Drive-by Compromise

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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