CVE-2021-30897Network attack vector

Cross-origin data exfiltration via resource timing API

Published Aug 24, 2021 · Updated Aug 3, 2024

Information disclosure in Apple macOS before 12.0 allows remote attackers to exfiltrate data cross-origin via a malicious website. WebKit's resource timing API exposed timing details for cross-origin resources contrary to the specification's restrictions. A victim must visit attacker-controlled web content, and the consequence is cross-origin confidentiality loss without integrity or availability impact.

CVSS severity6.5
Medium
EPSS probability1.71%
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 Apple macOS before 12.0 allows remote attackers to exfiltrate data cross-origin via a malicious website. WebKit's resource timing API exposed timing details for cross-origin resources contrary to the specification's restrictions. A victim must visit attacker-controlled web content, and the consequence is cross-origin confidentiality loss without integrity or availability impact.

The record

CVE
CVE-2021-30897
Published
Aug 24, 2021
Updated
Aug 3, 2024
Vendor
Apple
Product
macOS
Classifications
T1189
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 <12.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Apple · macOSversion=unspecified <12.0

Published CVSS scores

4.3NVDAV:N/AC:M/Au:N/C:P/I:N/A:N
6.5NVDCVSS: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.

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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

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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