CVE-2021-21181Public exploitNetwork attack vector

Autofill data disclosure via preview-value side channel

Published Mar 9, 2021 · Updated Aug 3, 2024

Side-channel leakage in Google Chrome before 89.0.4389.72 allows remote attackers to infer Autofill data through a crafted HTML page. Autofill preview exposes script-readable style changes when a candidate value matches, letting a page test many replicated drop-down values and infer the previewed entry. Exploitation requires a user to visit the page and move the pointer over an Autofill suggestion; the demonstrated consequence is disclosure of saved profile values such as email addresses.

CVSS severity6.5
Medium
EPSS probability1.60%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Side-channel leakage in Google Chrome before 89.0.4389.72 allows remote attackers to infer Autofill data through a crafted HTML page. Autofill preview exposes script-readable style changes when a candidate value matches, letting a page test many replicated drop-down values and infer the previewed entry. Exploitation requires a user to visit the page and move the pointer over an Autofill suggestion; the demonstrated consequence is disclosure of saved profile values such as email addresses.

The record

CVE
CVE-2021-21181
Published
Mar 9, 2021
Updated
Aug 3, 2024
Vendor
Google Cloud
Product
Google Chrome
Classifications
CWE-203, 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

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 <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

4.3NIST NVDAV:N/AC:M/Au:N/C:P/I:N/A:N
6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/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 exploitPublished

Weakness, pattern, technique

CWE-203Observable Discrepancy
T1189Drive-by Compromise

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo