Microsoft Windows up to Server 2019 Event Tracing use after free

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.
7.7$5k-$25k0.00

Summaryinfo

A vulnerability was found in Microsoft Windows up to Server 2019. It has been rated as very critical. Affected by this issue is some unknown functionality of the component Event Tracing. The manipulation leads to an unknown weakness. This vulnerability is uniquely identified as CVE-2021-34486. The attack is possible to be carried out remotely. Moreover, an exploit is present. To fix this issue, it is recommended to deploy a patch.

Detailsinfo

A vulnerability was found in Microsoft Windows up to Server 2019 (Operating System). It has been rated as very critical. This issue affects an unknown function of the component Event Tracing. Using CWE to declare the problem leads to CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. Impacted is confidentiality, integrity, and availability.

The weakness was disclosed 08/10/2021 as confirmed security guidance (Website). It is possible to read the advisory at portal.msrc.microsoft.com. The identification of this vulnerability is CVE-2021-34486. Technical details are unknown but an exploit is available. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 10/30/2025).

It is declared as attacked. The CISA Known Exploited Vulnerabilities Catalog lists this issue since 03/28/2022 with a due date of 04/18/2022:

Apply updates per vendor instructions.

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

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.1
VulDB Meta Temp Score: 7.7

VulDB Base Score: 8.8
VulDB Temp Score: 8.4
VulDB Vector: 🔍
VulDB Reliability: 🔍

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

NVD Base Score: 7.8
NVD Vector: 🔍

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

CVSSv2info

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

NVD Base Score: 🔍

Exploitinginfo

Class: Use after free
CWE: CWE-416 / CWE-119
CAPEC: 🔍
ATT&CK: 🔍

Physical: Partially
Local: Yes
Remote: Yes

Availability: 🔍
Status: Attacked

EPSS Score: 🔍
EPSS Percentile: 🔍

KEV Added: 🔍
KEV Due: 🔍
KEV Remediation: 🔍
KEV Ransomware: 🔍
KEV Notice: 🔍

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

06/09/2021 🔍
08/10/2021 +62 days 🔍
08/10/2021 +0 days 🔍
08/10/2021 +0 days 🔍
10/30/2025 +1542 days 🔍

Sourcesinfo

Vendor: microsoft.com
Product: microsoft.com

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

CVE: CVE-2021-34486 (🔍)
GCVE (CVE): GCVE-0-2021-34486
GCVE (VulDB): GCVE-100-180467
scip Labs: https://www.scip.ch/en/?labs.20161215

Entryinfo

Created: 08/10/2021 20:45
Updated: 10/30/2025 21:41
Changes: 08/10/2021 20:45 (27), 08/10/2021 20:46 (6), 08/10/2021 20:49 (22), 08/15/2021 08:54 (2), 04/25/2024 07:43 (29), 07/17/2024 13:04 (29), 09/19/2024 18:18 (2), 10/30/2025 21:41 (1)
Complete: 🔍
Cache ID: 216::103

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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