CVE-2023-21803Network attack vector

Unauthenticated code execution via undisclosed integer overflow

Published Feb 14, 2023 · Updated Aug 19, 2026

Integer overflow in Microsoft Windows iSCSI Discovery Service allows unauthenticated remote attackers to execute code over the network. Microsoft identifies the weakness as an integer overflow but does not disclose the affected field, arithmetic operation, or malformed iSCSI input that triggers it. Exploitation requires network reachability to the discovery service on an affected 32-bit Windows build and grants code execution in the service context.

CVSS severity9.8
Critical
EPSS probability1.76%
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 Microsoft Windows iSCSI Discovery Service allows unauthenticated remote attackers to execute code over the network. Microsoft identifies the weakness as an integer overflow but does not disclose the affected field, arithmetic operation, or malformed iSCSI input that triggers it. Exploitation requires network reachability to the discovery service on an affected 32-bit Windows build and grants code execution in the service context.

The record

CVE
CVE-2023-21803
Published
Feb 14, 2023
Updated
Aug 19, 2026
Vendor
Microsoft
Product
Windows 10 Version 1507
Classifications
CWE-190, T1210
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 14, 2023CVE publishedPublication date reported by the CVE source.
  2. Aug 19, 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=10.0.10240.0 <10.0.10240.19747

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft · Windows 10 Version 1507version=10.0.10240.0 <10.0.10240.19747
Microsoft · Windows 10 Version 21H2version=10.0.19043.0 <10.0.19044.2604
Microsoft · Windows 10 Version 20H2version=10.0.0 <10.0.19042.2604
Microsoft · Windows 10 Version 22H2version=10.0.19045.0 <10.0.19045.2604
Microsoft · Windows 10 Version 1607version=10.0.14393.0 <10.0.14393.5717
Microsoft · Windows Server 2008 Service Pack 2version=6.0.6003.0 <6.0.6003.21915
Microsoft · Windows 10 Version 1809version=10.0.17763.0 <10.0.17763.4010
Microsoft · Windows Server 2008 Service Pack 2 (Server Core installation)version=6.0.6003.0 <6.0.6003.21915

Published CVSS scores

9.8Microsoft CorporationCVSS:3.1/AV:N/AC:L/PR:N/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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-190Integer Overflow or Wraparound
T1210Exploitation of Remote Services

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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