CVE-2021-1790Public exploit

Arbitrary code execution via unchecked font offsets

Published Apr 2, 2021 · Updated Aug 3, 2024

Out-of-bounds read in Apple macOS FontParser before 11.2 allows attackers to execute arbitrary code via a malicious font. The hvf::LoaderCBF::loadPartAtIndex routine in libhvf.dylib trusts attacker-controlled HierVariation start and end offsets without checking them against the font buffer. Exploitation requires enabling HVFEnabled in a per-user FontParser preference and opening the crafted font through Font Book, limiting exposure to that non-default configuration.

CVSS severity7.8
High
EPSS probability1.00%
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 macOS FontParser before 11.2 allows attackers to execute arbitrary code via a malicious font. The hvf::LoaderCBF::loadPartAtIndex routine in libhvf.dylib trusts attacker-controlled HierVariation start and end offsets without checking them against the font buffer. Exploitation requires enabling HVFEnabled in a per-user FontParser preference and opening the crafted font through Font Book, limiting exposure to that non-default configuration.

The record

CVE
CVE-2021-1790
Published
Apr 2, 2021
Updated
Aug 3, 2024
Vendor
Apple
Product
macOS
Classifications
CWE-125, T1204.002, T1203
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 <11.2

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Apple · macOSversion=unspecified <11.2

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 exploitPublished

Weakness, pattern, technique

CWE-125Out-of-bounds Read
T1204.002User Execution Malicious File
T1203Exploitation for Client Execution

Public exploit references

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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