Microsoft Windows up to Server 2022 Fax Service Remote Code Execution

CVSS Meta Temp Score
CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.
Current Exploit Price (≈)
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CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
7.3$5k-$25k0.00

Summaryinfo

A vulnerability marked as critical has been reported in Microsoft Windows. This impacts an unknown function of the component Fax Service. Performing a manipulation results in an unknown weakness. This vulnerability is identified as CVE-2021-43234. The attack can be initiated remotely. There is not any exploit 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 classified as critical. This affects an unknown code of the component Fax Service. This is going to have an impact on confidentiality, integrity, and availability.

The weakness was released 12/14/2021 as confirmed security guidance (Website). The advisory is shared at portal.msrc.microsoft.com. This vulnerability is uniquely identified as CVE-2021-43234. It demands that the victim is doing some kind of user interaction. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 10/07/2025).

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: 8.3
VulDB Meta Temp Score: 7.3

VulDB Base Score: 8.8
VulDB Temp Score: 7.7
VulDB Vector: 🔍
VulDB Reliability: 🔍

Vendor Base Score (Microsoft): 7.8
Vendor Vector (Microsoft): 🔍

CVSSv2info

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

Exploitinginfo

Class: Remote Code Execution
CWE: Unknown
CAPEC: 🔍
ATT&CK: 🔍

Physical: Partially
Local: Yes
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-2021-43234 (🔍)
GCVE (CVE): GCVE-0-2021-43234
GCVE (VulDB): GCVE-100-188241
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 05:56
Updated: 10/07/2025 19:53
Changes: 12/15/2021 05:56 (33), 12/15/2021 06:00 (21), 12/17/2021 14:26 (2), 10/07/2025 19:53 (22)
Complete: 🔍
Cache ID: 216::103

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

Discussion

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