CVE-2021-24083

Code execution via WAB out-of-bounds write

Published Feb 25, 2021 · Updated Nov 19, 2024

Windows Address Book in Microsoft Windows releases before the February 2021 update allows remote attackers to execute code via a malicious WAB file. The wab32 parser fails to validate user-supplied file data and writes past an allocated buffer. Exploitation requires a user to open the file or visit a page that supplies it, enabling code execution with the current process privileges.

CVSS severity6.8
Medium
EPSS probability2.87%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Windows Address Book in Microsoft Windows releases before the February 2021 update allows remote attackers to execute code via a malicious WAB file. The wab32 parser fails to validate user-supplied file data and writes past an allocated buffer. Exploitation requires a user to open the file or visit a page that supplies it, enabling code execution with the current process privileges.

The record

CVE
CVE-2021-24083
Published
Feb 25, 2021
Updated
Nov 19, 2024
Vendor
Microsoft
Product
Windows 10 Version 1507
Classifications
CWE-787, T1203
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 25, 2021CVE publishedPublication date reported by the CVE source.
  2. Nov 19, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=10.0.0 <publication

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Microsoft · Windows 10 Version 1507version=10.0.0 <publication
Microsoft · Windows Server 2019version=10.0.0 <publication
Microsoft · Windows 7version=6.1.0 <publication
Microsoft · Windows 10 Version 1909version=10.0.0 <publication
Microsoft · Windows 10 Version 1803version=10.0.0 <publication
Microsoft · Windows 8.1version=6.3.0 <publication
Microsoft · Windows Server 2016 (Server Core installation)version=10.0.0 <publication
Microsoft · Windows Server 2012 (Server Core installation)version=6.2.0 <publication
Microsoft · Windows Server 2012version=6.2.0 <publication
Microsoft · Windows Server, version 2004version=10.0.0 <publication
Microsoft · Windows Server 2016version=10.0.0 <publication
Microsoft · Windows Server 2008 R2 Service Pack 1version=6.1.0 <publication
Microsoft · Windows 10 Version 20H2version=10.0.0 <publication
Microsoft · Windows Server 2008 R2 Service Pack 1 (Server Core installation)version=6.0.0 <publication
Microsoft · Windows Server 2012 R2 (Server Core installation)version=6.3.0 <publication
Microsoft · Windows Server 2019 (Server Core installation)version=10.0.0 <publication
Microsoft · Windows 7 Service Pack 1version=6.1.0 <publication
Microsoft · Windows Server version 20H2version=10.0.0 <publication
Microsoft · Windows 10 Version 1607version=10.0.0 <publication
Microsoft · Windows 10 Version 2004version=10.0.0 <publication
Microsoft · Windows 10 Version 1809version=10.0.0 <publication
Microsoft · Windows Server 2012 R2version=6.3.0 <publication
Microsoft · Windows Server, version 1909 (Server Core installation)version=10.0.0 <publication

Published CVSS scores

6.8NVDAV:N/AC:M/Au:N/C:P/I:P/A:P
7.8MicrosoftCVSS:3.1/AV:L/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
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.

Technologies

Your stack

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Your stack

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