CVE-2021-30789

Arbitrary code execution via CoreText TTF over-read

Published Sep 8, 2021 · Updated Aug 3, 2024

Out-of-bounds read in Apple CoreText before iOS 14.7 and macOS 11.5 allows context-dependent attackers to execute code via a crafted font file. The TTF parser reads crafted font data past the end of an allocated data structure because input bounds are not validated. A user or application must cause CoreText to process the font; the over-read can disclose process memory and support code execution when chained.

CVSS severity7.8
High
EPSS probability1.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in Apple CoreText before iOS 14.7 and macOS 11.5 allows context-dependent attackers to execute code via a crafted font file. The TTF parser reads crafted font data past the end of an allocated data structure because input bounds are not validated. A user or application must cause CoreText to process the font; the over-read can disclose process memory and support code execution when chained.

The record

CVE
CVE-2021-30789
Published
Sep 8, 2021
Updated
Aug 3, 2024
Vendor
Apple
Product
iOS
Classifications
CWE-125, T1203
Attack vector
local
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 <14.7

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Apple · iOSversion=unspecified <14.7
Apple · Security Update Catalinaversion=unspecified <2021
Apple · macOSversion=unspecified <11.5; version=unspecified <14.7; version=unspecified <7.6

Published CVSS scores

7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
6.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/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.

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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)
Vectorlocal
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.

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Technologies

Your stack

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Your stack

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