Microsoft Windows up to Server 2022 iSNS Server memory corruption

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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8.5$25k-$100k0.00

Summaryinfo

A vulnerability identified as very critical has been detected in Microsoft Windows. This issue affects some unknown processing of the component iSNS Server. The manipulation leads to memory corruption. This vulnerability is referenced as CVE-2021-43215. Remote exploitation of the attack is possible. No exploit is available. It is suggested to install a patch to address this issue.

Detailsinfo

A vulnerability was found in Microsoft Windows (Operating System). It has been rated as very critical. This issue affects some unknown functionality of the component iSNS Server. The manipulation with an unknown input leads to a memory corruption vulnerability. Using CWE to declare the problem leads to CWE-119. The product performs operations on a memory buffer, but it can read from or write to a memory location that is outside of the intended boundary of the buffer. Impacted is confidentiality, integrity, and availability.

The weakness was published 12/14/2021 as confirmed security guidance (Website). The advisory is shared at portal.msrc.microsoft.com. The identification of this vulnerability is CVE-2021-43215. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $25k-$100k at the moment (estimation calculated on 10/07/2025).

We expect the 0-day to have been worth approximately $100k and more.

Applying a patch is able to eliminate this problem. A possible mitigation has been published immediately after the disclosure of the vulnerability.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2025-2220). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Affected

  • Microsoft Windows 7 x64 Edition Service Pack 1
  • Microsoft Windows RT 8.1
  • Microsoft Windows 8.1 for x64-based Systems
  • Microsoft Windows 10
  • Microsoft Windows Server 2012
  • Microsoft Windows Server 2016
  • Hitachi Storage
  • Microsoft Windows Server 2008 Service Pack 2
  • Microsoft Windows Server 2008 R2
  • Microsoft Windows Server 2019
  • Microsoft Windows Server 2012 R2
  • Microsoft Windows Server
  • Microsoft Windows Server 2022
  • Microsoft Windows 11

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 9.8
VulDB Meta Temp Score: 8.5

VulDB Base Score: 9.8
VulDB Temp Score: 8.5
VulDB Vector: 🔍
VulDB Reliability: 🔍

Vendor Base Score (Microsoft): 9.8
Vendor Vector (Microsoft): 🔍

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

Exploitinginfo

Class: Memory corruption
CWE: CWE-119
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Yes

Availability: 🔍
Status: Unproven

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Patch
Status: 🔍

Reaction Time: 🔍
0-Day Time: 🔍
Exposure Time: 🔍

Timelineinfo

11/02/2021 🔍
12/14/2021 +42 days 🔍
12/14/2021 +0 days 🔍
12/15/2021 +0 days 🔍
10/07/2025 +1392 days 🔍

Sourcesinfo

Vendor: microsoft.com
Product: microsoft.com

Advisory: portal.msrc.microsoft.com
Status: Confirmed

CVE: CVE-2021-43215 (🔍)
GCVE (CVE): GCVE-0-2021-43215
GCVE (VulDB): GCVE-100-188225
CERT Bund: WID-SEC-2025-2220 - Microsoft Windows und Microsoft Windows Server: Mehrere Schwachstellen

scip Labs: https://www.scip.ch/en/?labs.20161215

Entryinfo

Created: 12/15/2021 05:38
Updated: 10/07/2025 18:28
Changes: 12/15/2021 05:38 (27), 12/15/2021 05:39 (7), 12/15/2021 05:42 (22), 12/17/2021 13:14 (2), 10/07/2025 18:28 (21)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Discussion

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