CVE-2020-1020Known exploitationNetwork attack vector

Code execution via malformed Type 1 fonts

Published Apr 15, 2020 · Updated Oct 21, 2025

Out-of-bounds write in the Windows Adobe Type Manager Library allows remote attackers to execute code via a crafted Type 1 font. The font parser writes beyond an allocated buffer while processing a specially crafted multi-master Adobe Type 1 PostScript font. A user must open or preview a malicious document; Windows 10 build 1709 and later parse fonts in a sandbox, limiting impact without a sandbox escape.

CVSS severity8.8
High
EPSS probability65.04%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds write in the Windows Adobe Type Manager Library allows remote attackers to execute code via a crafted Type 1 font. The font parser writes beyond an allocated buffer while processing a specially crafted multi-master Adobe Type 1 PostScript font. A user must open or preview a malicious document; Windows 10 build 1709 and later parse fonts in a sandbox, limiting impact without a sandbox escape.

The record

CVE
CVE-2020-1020
Published
Apr 15, 2020
Updated
Oct 21, 2025
Vendor
Microsoft
Product
Windows 10 Version 1909
Classifications
CWE-787, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 15, 2020CVE publishedPublication date reported by the CVE source.
  2. Nov 3, 2021Exploitation reportedCISA Known Exploited Vulnerabilities Catalog inclusion
  3. Oct 21, 2025Record 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

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft · Windows 10 Version 1909version=unspecified
Microsoft · Windows Server, version 1903 (Server Core installation)version=unspecified
Microsoft · Windowsversion=10 for 32-bit Systems; version=10 for x64-based Systems; version=10 Version 1607 for 32-bit Systems; version=10 Version 1607 for x64-based Systems; version=10 Version 1709 for 32-bit Systems; version=10 Version 1709 for ARM64-based Systems; version=10 Version 1709 for x64-based Systems; version=10 Version 1803 for 32-bit Systems; version=10 Version 1803 for ARM64-based Systems; version=10 Version 1803 for x64-based Systems; version=10 Version 1809 for 32-bit Systems; version=10 Version 1809 for ARM64-based Systems; version=10 Version 1809 for x64-based Systems; version=7 for 32-bit Systems Service Pack 1; version=7 for x64-based Systems Service Pack 1; version=8.1 for 32-bit systems; version=8.1 for x64-based systems; version=RT 8.1
Microsoft · Windows Serverversion=2008 for 32-bit Systems Service Pack 2; version=2008 for 32-bit Systems Service Pack 2 (Core installation); version=2008 for Itanium-Based Systems Service Pack 2; version=2008 for x64-based Systems Service Pack 2; version=2008 for x64-based Systems Service Pack 2 (Core installation); version=2008 R2 for Itanium-Based Systems Service Pack 1; version=2008 R2 for x64-based Systems Service Pack 1; version=2008 R2 for x64-based Systems Service Pack 1 (Core installation); version=2012; version=2012 (Core installation); version=2012 R2; version=2012 R2 (Core installation); version=2016; version=2016 (Core installation); version=2019; version=2019 (Core installation); version=version 1803 (Core Installation)
Microsoft · Windows Server, version 1909 (Server Core installation)version=unspecified
Microsoft · Windows 10 Version 1903version=unspecified

Published CVSS scores

8.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
8.8NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
6.8NIST National Vulnerability DatabaseAV: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.

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)
Vectornetwork
Privilegesunauthenticated
Known exploitationReported
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
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.

Reported exploitation

Technologies

Your stack

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Your stack

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