CVE-2020-9956Network attack vector

Code execution via FontParser font read

Published Apr 2, 2021 · Updated Aug 4, 2024

Apple operating systems before the listed fixed releases allow remote attackers to execute arbitrary code via maliciously crafted font files. The FontParser component performs an out-of-bounds read while processing attacker-controlled font data, with improved input validation correcting the memory-boundary failure. Exploitation requires a victim to process the font, such as opening a file or viewing content that invokes font parsing; the crafted input can then corrupt process memory and execute code.

CVSS severity7.8
High
EPSS probability1.08%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Apple operating systems before the listed fixed releases allow remote attackers to execute arbitrary code via maliciously crafted font files. The FontParser component performs an out-of-bounds read while processing attacker-controlled font data, with improved input validation correcting the memory-boundary failure. Exploitation requires a victim to process the font, such as opening a file or viewing content that invokes font parsing; the crafted input can then corrupt process memory and execute code.

The record

CVE
CVE-2020-9956
Published
Apr 2, 2021
Updated
Aug 4, 2024
Vendor
Apple
Product
iOS and iPadOS
Classifications
CWE-125, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 2, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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 <14.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Apple · iOS and iPadOSversion=unspecified <14.0
Apple · tvOSversion=unspecified <14.0
Apple · macOSversion=unspecified <11.0; version=unspecified <11.1
Apple · watchOSversion=unspecified <7.0

Published CVSS scores

7.8NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

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-125Out-of-bounds Read
T1203Exploitation for Client Execution

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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