CVE-2020-6623Public exploit

Application crash via invalid CFF offset size

Published Jan 8, 2020 · Updated Aug 4, 2024

An assertion failure in stb_truetype.h through 1.22 allows attackers to crash applications that parse a crafted OpenType font. The stbtt__cff_get_index parser reads the CFF INDEX offSize byte from the file and asserts that it is between 1 and 4 instead of rejecting an invalid value. Reachability requires an application to pass an attacker-supplied font to stbtt_InitFont; the demonstrated consequence is process abort and service interruption.

CVSS severityUnavailable
Unscored
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

An assertion failure in stb_truetype.h through 1.22 allows attackers to crash applications that parse a crafted OpenType font. The stbtt__cff_get_index parser reads the CFF INDEX offSize byte from the file and asserts that it is between 1 and 4 instead of rejecting an invalid value. Reachability requires an application to pass an attacker-supplied font to stbtt_InitFont; the demonstrated consequence is process abort and service interruption.

The record

CVE
CVE-2020-6623
Published
Jan 8, 2020
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
Unavailable
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

No CVSS assessment is available in this record.

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
VectorUnavailable
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

No sourced classifications are available.

Public exploit references

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Technologies

Your stack

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Your stack

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