Microsoft Exchange Server up to 2019 CU9 ProxyShell unrestricted upload

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 (≈)
Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.
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.
6.3$0-$5k0.00

Summaryinfo

A vulnerability, which was classified as critical, was found in Microsoft Exchange Server 2013 CU23/2016 CU19/2016 CU20/2019 CU8/2019 CU9. Affected by this vulnerability is an unknown functionality. The manipulation results in an unknown weakness. This vulnerability is cataloged as CVE-2021-31207. The attack may be launched remotely. Furthermore, there is an exploit available. A patch should be applied to remediate this issue.

Detailsinfo

A vulnerability classified as critical has been found in Microsoft Exchange Server 2013 CU23/2016 CU19/2016 CU20/2019 CU8/2019 CU9 (Groupware Software). CWE is classifying the issue as CWE-434. The product allows the attacker to upload or transfer files of dangerous types that can be automatically processed within the product's environment. This is going to have an impact on confidentiality, integrity, and availability.

The weakness was shared 05/11/2021 as confirmed security guidance (Website). The advisory is available at portal.msrc.microsoft.com. This vulnerability is traded as CVE-2021-31207. Technical details are unknown but an exploit is available. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 02/05/2025). This vulnerability is assigned to T1608.002 by the MITRE ATT&CK project.

It is declared as attacked. This issue was added on 11/03/2021 to the CISA Known Exploited Vulnerabilities Catalog with a due date of 11/17/2021:

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.

If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.6
VulDB Meta Temp Score: 6.3

VulDB Base Score: 6.6
VulDB Temp Score: 6.3
VulDB Vector: 🔍
VulDB Reliability: 🔍

Vendor Base Score (Microsoft): 6.6
Vendor Vector (Microsoft): 🔍

NVD Base Score: 6.6
NVD Vector: 🔍

CNA Base Score: 6.6
CNA 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: 🔍

NVD Base Score: 🔍

Exploitinginfo

Class: Unrestricted upload
CWE: CWE-434 / CWE-284 / CWE-266
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
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

04/14/2021 🔍
05/11/2021 +27 days 🔍
05/11/2021 +0 days 🔍
05/12/2021 +0 days 🔍
02/05/2025 +1365 days 🔍

Sourcesinfo

Vendor: microsoft.com

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

CVE: CVE-2021-31207 (🔍)
GCVE (CVE): GCVE-0-2021-31207
GCVE (VulDB): GCVE-100-174834
scip Labs: https://www.scip.ch/en/?labs.20161013

Entryinfo

Created: 05/12/2021 06:31
Updated: 02/05/2025 08:16
Changes: 05/12/2021 06:31 (29), 05/12/2021 06:32 (5), 05/12/2021 06:35 (19), 05/13/2021 12:16 (2), 12/13/2021 11:28 (1), 04/21/2024 19:00 (29), 07/26/2024 21:49 (27), 09/15/2024 13:07 (2), 02/05/2025 08:16 (1)
Complete: 🔍
Cache ID: 216::103

If you want to get best quality of vulnerability data, you may have to visit VulDB.

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