CVE-2021-30840

Arbitrary code execution

Published Oct 28, 2021 · Updated Aug 3, 2024

Code execution in Apple FontParser in iOS, iPadOS, and tvOS before 15 and watchOS before 8 allows attackers to run code via a crafted dfont file. FontParser processes attacker-controlled dfont data with checks that Apple describes only as insufficient; Apple has not disclosed the faulty operation or code-level locus. Exploitation requires a target to process the crafted font and can execute arbitrary code in the parsing process; public sources do not establish remote delivery, privilege gain, or sandbox escape.

CVSS severity7.8
High
EPSS probability1.06%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Code execution in Apple FontParser in iOS, iPadOS, and tvOS before 15 and watchOS before 8 allows attackers to run code via a crafted dfont file. FontParser processes attacker-controlled dfont data with checks that Apple describes only as insufficient; Apple has not disclosed the faulty operation or code-level locus. Exploitation requires a target to process the crafted font and can execute arbitrary code in the parsing process; public sources do not establish remote delivery, privilege gain, or sandbox escape.

The record

CVE
CVE-2021-30840
Published
Oct 28, 2021
Updated
Aug 3, 2024
Vendor
Apple
Product
iOS and iPadOS
Classifications
T1203
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 28, 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 <15

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Apple · iOS and iPadOSversion=unspecified <15
Apple · tvOSversion=unspecified <15
Apple · watchOSversion=unspecified <8

Published CVSS scores

6.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/A:P
7.8NIST NVDCVSS: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)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

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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