Microsoft Exchange Server up to 2019 CU8 path traversal

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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7.2$0-$5k0.00

Summaryinfo

A vulnerability was found in Microsoft Exchange Server 2013 CU23/2016 CU18/2016 CU19/2019 CU7/2019 CU8. It has been classified as critical. The impacted element is an unknown function. Performing a manipulation results in an unknown weakness. This vulnerability is known as CVE-2021-27065. Remote exploitation of the attack is possible. Furthermore, an exploit is available. To fix this issue, it is recommended to deploy a patch.

Detailsinfo

A vulnerability classified as critical has been found in Microsoft Exchange Server 2013 CU23/2016 CU18/2016 CU19/2019 CU7/2019 CU8 (Groupware Software). CWE is classifying the issue as CWE-22. The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. This is going to have an impact on confidentiality, integrity, and availability.

The weakness was published 03/02/2021 as confirmed security guidance (Website). It is possible to read the advisory at portal.msrc.microsoft.com. This vulnerability is uniquely identified as CVE-2021-27065. It demands that the victim is doing some kind of user interaction. Technical details are unknown but a public exploit is available. The attack technique deployed by this issue is T1006 according to MITRE ATT&CK.

A public exploit has been developed by Jang (testanull) in Python and been published 2 weeks after the advisory. The exploit is shared for download at testbnull.medium.com. It is declared as attacked. We expect the 0-day to have been worth approximately $25k-$100k. The CISA Known Exploited Vulnerabilities Catalog lists this issue since 11/03/2021 with a due date of 05/03/2022:

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.

The vulnerability is also documented in the databases at Exploit-DB (49637) and Zero-Day.cz (609). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

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Website

CPE 2.3info

CPE 2.2info

Video

Youtube: Not available anymore

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.4
VulDB Meta Temp Score: 7.2

VulDB Base Score: 6.3
VulDB Temp Score: 6.0
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: 🔍

CVSSv2info

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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
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NVD Base Score: 🔍

Exploitinginfo

Class: Path traversal
CWE: CWE-22
CAPEC: 🔍
ATT&CK: 🔍

Physical: Partially
Local: Yes
Remote: Yes

Availability: 🔍
Access: Public
Status: Attacked
Author: Jang (testanull)
Programming Language: 🔍
Download: 🔍

EPSS Score: 🔍
EPSS Percentile: 🔍

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

Price Prediction: 🔍
Current Price Estimation: 🔍

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Exploit-DB: 🔍
Zero-Day.cz: 🔍

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Patch
Status: 🔍

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

Timelineinfo

02/10/2021 🔍
03/02/2021 +20 days 🔍
03/02/2021 +0 days 🔍
03/03/2021 +0 days 🔍
03/11/2021 +7 days 🔍
12/17/2025 +1742 days 🔍

Sourcesinfo

Vendor: microsoft.com

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

CVE: CVE-2021-27065 (🔍)
GCVE (CVE): GCVE-0-2021-27065
GCVE (VulDB): GCVE-100-170595
scip Labs: https://www.scip.ch/en/?labs.20161013

Entryinfo

Created: 03/03/2021 08:26
Updated: 12/17/2025 19:09
Changes: 03/03/2021 08:26 (29), 03/03/2021 08:29 (23), 03/06/2021 12:28 (2), 03/12/2021 07:43 (4), 03/12/2021 07:44 (5), 03/14/2021 12:14 (18), 04/21/2024 12:12 (29), 06/30/2024 01:50 (2), 07/08/2024 19:21 (1), 07/25/2024 22:17 (13), 09/12/2024 23:36 (2), 01/19/2025 22:31 (1), 05/04/2025 05:08 (3), 10/30/2025 21:18 (1), 12/17/2025 19:09 (1)
Complete: 🔍
Committer: misc
Cache ID: 216::103

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

Discussion

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