CVE-2021-1766

Application termination via malicious image processing

Published Apr 2, 2021 · Updated Aug 3, 2024

Denial of service in Apple ImageIO in iOS and iPadOS before 14.4 and macOS Big Sur before 11.2 allows attackers to terminate applications. Apple identifies insufficient checks during malicious image processing but has not disclosed the failing parser operation or validation condition. Exploitation requires a user to process a crafted image; the documented consequence is application termination, with no reported data disclosure or modification.

CVSS severity5.5
Medium
EPSS probability0.81%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Apple ImageIO in iOS and iPadOS before 14.4 and macOS Big Sur before 11.2 allows attackers to terminate applications. Apple identifies insufficient checks during malicious image processing but has not disclosed the failing parser operation or validation condition. Exploitation requires a user to process a crafted image; the documented consequence is application termination, with no reported data disclosure or modification.

The record

CVE
CVE-2021-1766
Published
Apr 2, 2021
Updated
Aug 3, 2024
Vendor
Apple
Product
iOS and iPadOS
Classifications
T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 2, 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 <14.4

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Apple · iOS and iPadOSversion=unspecified <14.4
Apple · macOSversion=unspecified <11.2; version=unspecified <14.4; version=unspecified <7.3

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:N/A:P

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)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1204.002User Execution: Malicious File

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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