CVE-2021-34513

SYSTEM code execution via storport integer overflow

Published Jul 14, 2021 · Updated Aug 10, 2026

Integer overflow in the Windows storport.sys driver allows local users to execute arbitrary code with SYSTEM privileges. An input-length calculation can wrap before buffer allocation because the driver does not properly validate user-supplied data. Exploitation requires prior low-privileged code execution on an affected host and grants complete SYSTEM-level control over data and services.

CVSS severity7.8
High
EPSS probability1.05%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Integer overflow in the Windows storport.sys driver allows local users to execute arbitrary code with SYSTEM privileges. An input-length calculation can wrap before buffer allocation because the driver does not properly validate user-supplied data. Exploitation requires prior low-privileged code execution on an affected host and grants complete SYSTEM-level control over data and services.

The record

CVE
CVE-2021-34513
Published
Jul 14, 2021
Updated
Aug 10, 2026
Vendor
Microsoft
Product
Windows 10 Version 21H1
Classifications
CWE-190, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 14, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 10, 2026Record 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=10.0.0 <10.0.19043.1110

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Microsoft · Windows 10 Version 21H1version=10.0.0 <10.0.19043.1110
Microsoft · Windows 10 Version 1909version=10.0.0 <10.0.18363.1679
Microsoft · Windows Server, version 2004version=10.0.0 <10.0.19041.1110
Microsoft · Windows 10 Version 20H2version=10.0.0 <10.0.19042.1110
Microsoft · Windows Server version 20H2version=10.0.0 <10.0.19042.1110
Microsoft · Windows 10 Version 2004version=10.0.0 <10.0.19041.1110

Published CVSS scores

7.8MicrosoftCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.2NIST NVDAV:L/AC:L/Au:N/C:C/I:C/A:C
7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-190Integer Overflow or Wraparound
T1068Exploitation for Privilege Escalation

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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