CVE-2020-6622Public exploit

Application crash via out-of-bounds CFF dictionary read

Published Jan 8, 2020 · Updated Aug 4, 2024

Heap-based buffer over-read in stb_truetype.h through 1.22 allows attackers to crash font-processing applications via a crafted CFF font. During CFF dictionary parsing, stbtt__dict_get calls stbtt__buf_peek8 after the parser cursor leaves the allocated font buffer, and the helper reads one byte outside the heap allocation. The application must process an attacker-supplied OpenType/CFF font; the published proof of concept terminates under AddressSanitizer, so the demonstrated consequence is an application crash.

CVSS severity8.8
High
EPSS probability1.45%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap-based buffer over-read in stb_truetype.h through 1.22 allows attackers to crash font-processing applications via a crafted CFF font. During CFF dictionary parsing, stbtt__dict_get calls stbtt__buf_peek8 after the parser cursor leaves the allocated font buffer, and the helper reads one byte outside the heap allocation. The application must process an attacker-supplied OpenType/CFF font; the published proof of concept terminates under AddressSanitizer, so the demonstrated consequence is an application crash.

The record

CVE
CVE-2020-6622
Published
Jan 8, 2020
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
T1499.004
Attack vector
Unavailable
Privileges
Unavailable

Timeline

How it unfolded

  1. Jan 8, 2020CVE 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorUnavailable in this record.
Required privilegesUnavailable in this record.

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

8.8CanonicalCVSS:3.1/AV:N/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.

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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)
VectorUnavailable
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

T1499.004Application or System Exploitation

Public exploit references

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Technologies

Your stack

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Your stack

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