CVE-2021-30884Network attack vector

Browsing-history disclosure via insufficient CSS compositing restrictions

Published Aug 24, 2021 · Updated Aug 3, 2024

Information disclosure in WebKit before iOS 15, iPadOS 15, tvOS 15, and watchOS 8 allows remote attackers to read browsing history. WebKit applies insufficient restrictions while compositing CSS from a crafted page, allowing the page to distinguish previously visited sites. Exploitation requires a user to visit the crafted website; the documented consequence is browsing-history disclosure, not data modification or service interruption.

CVSS severity4.7
Medium
EPSS probability1.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in WebKit before iOS 15, iPadOS 15, tvOS 15, and watchOS 8 allows remote attackers to read browsing history. WebKit applies insufficient restrictions while compositing CSS from a crafted page, allowing the page to distinguish previously visited sites. Exploitation requires a user to visit the crafted website; the documented consequence is browsing-history disclosure, not data modification or service interruption.

The record

CVE
CVE-2021-30884
Published
Aug 24, 2021
Updated
Aug 3, 2024
Vendor
Apple
Product
iOS and iPadOS
Classifications
CWE-200, T1217
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 24, 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 <15

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Apple · iOS and iPadOSversion=unspecified <15
Apple · tvOSversion=unspecified <15
Apple · watchOSversion=unspecified <8

Published CVSS scores

4.7NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N
4.3NVDAV:N/AC:M/Au:N/C:P/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 exploitUnconfirmed

Weakness, pattern, technique

CWE-200Exposure of Sensitive Information to an Unauthorized Actor
T1217Browser Information Discovery

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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