CVE-2021-1857Network attack vector

Sensitive information disclosure via uninitialized CFNetwork memory

Published Sep 8, 2021 · Updated Aug 3, 2024

Improper memory initialization in CFNetwork across affected Apple products allows attackers to disclose sensitive data via crafted web content. CFNetwork processes attacker-controlled web content without fully initializing memory, allowing residual memory contents to become observable. Reachability requires an affected application or system service to process the crafted content; Apple has not disclosed the specific code path or data exposed.

CVSS severityUnavailable
Unscored
EPSS probability1.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper memory initialization in CFNetwork across affected Apple products allows attackers to disclose sensitive data via crafted web content. CFNetwork processes attacker-controlled web content without fully initializing memory, allowing residual memory contents to become observable. Reachability requires an affected application or system service to process the crafted content; Apple has not disclosed the specific code path or data exposed.

The record

CVE
CVE-2021-1857
Published
Sep 8, 2021
Updated
Aug 3, 2024
Vendor
Apple
Product
iTunes for Windows
Classifications
CWE-665
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 8, 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 <12.11

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Apple · iTunes for Windowsversion=unspecified <12.11
Apple · iOS and iPadOSversion=unspecified <14.5
Apple · iCloud for Windowsversion=unspecified <12.3
Apple · tvOSversion=unspecified <14.5
Apple · macOSversion=unspecified <11.3; version=unspecified <2021
Apple · watchOSversion=unspecified <7.4

Published CVSS scores

No CVSS assessment is available in this record.

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-665Improper Initialization

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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