CVE-2021-1837Network attack vector

Traffic alteration via certificate validation failure

Published Sep 8, 2021 · Updated Aug 3, 2024

Certificate validation failure in the Apple App Store before iOS and iPadOS 14.5 allows man-in-the-middle attackers to alter traffic. Apple has not published which certificate check the App Store performs incorrectly or what crafted certificate input triggers the failure. Exploitation requires a privileged network position, and the published consequence is limited to modification of App Store network traffic.

CVSS severityUnavailable
Unscored
EPSS probability0.49%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Certificate validation failure in the Apple App Store before iOS and iPadOS 14.5 allows man-in-the-middle attackers to alter traffic. Apple has not published which certificate check the App Store performs incorrectly or what crafted certificate input triggers the failure. Exploitation requires a privileged network position, and the published consequence is limited to modification of App Store network traffic.

The record

CVE
CVE-2021-1837
Published
Sep 8, 2021
Updated
Aug 3, 2024
Vendor
Apple
Product
iOS and iPadOS
Classifications
T1557
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 <14.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Apple · iOS and iPadOSversion=unspecified <14.5

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.

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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

T1557Adversary-in-the-Middle

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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