Microsoft Exchange Server Security Feature Bypass Vulnerability
Priority CRITICAL 88Exploited in the wildCWE-434Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- High
- User interaction
- None
- Attack complexity
- High
- Impact type
- Code execution
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-434.
Summary
Microsoft Exchange Server Security Feature Bypass Vulnerability
Why it matters now
Exploitation Active In CISA KEV since 2021-11-03CISA due date 2021-11-17Known ransomware use
EPSS 0.99782 99th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed Microsoft Exchange Server 2013 Cumulative Update 23 (Microsoft): 15.00.1497.018Microsoft Exchange Server 2019 Cumulative Update 9 (Microsoft): 15.02.0858.012+3 more products
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Active
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Microsoft | Microsoft Exchange Server 2013 Cumulative Update 23 | 15.00.0 to before 15.00.1497.018 | 15.00.1497.018 | Patch available | CNA |
| Microsoft | Microsoft Exchange Server 2019 Cumulative Update 9 | 15.02.0 to before 15.02.0858.012 | 15.02.0858.012 | Patch available | CNA |
| Microsoft | Microsoft Exchange Server 2016 Cumulative Update 20 | 15.01.0 to before 15.01.2242.010 | 15.01.2242.010 | Patch available | CNA |
| Microsoft | Microsoft Exchange Server 2016 Cumulative Update 19 | 15.01.0 to before 15.01.2176.014 | 15.01.2176.014 | Patch available | CNA |
| Microsoft | Microsoft Exchange Server 2019 Cumulative Update 8 | 15.02.0 to before 15.02.0792.015 | 15.02.0792.015 | Patch available | CNA |
- Microsoft Exchange Server 2013 Cumulative Update 23 VendorMicrosoft Affected 15.00.0 to before 15.00.1497.018 Fixed in 15.00.1497.018 Patch available CNA
- Microsoft Exchange Server 2019 Cumulative Update 9 VendorMicrosoft Affected 15.02.0 to before 15.02.0858.012 Fixed in 15.02.0858.012 Patch available CNA
- Microsoft Exchange Server 2016 Cumulative Update 20 VendorMicrosoft Affected 15.01.0 to before 15.01.2242.010 Fixed in 15.01.2242.010 Patch available CNA
- Microsoft Exchange Server 2016 Cumulative Update 19 VendorMicrosoft Affected 15.01.0 to before 15.01.2176.014 Fixed in 15.01.2176.014 Patch available CNA
- Microsoft Exchange Server 2019 Cumulative Update 8 VendorMicrosoft Affected 15.02.0 to before 15.02.0792.015 Fixed in 15.02.0792.015 Patch available CNA
CPE configurations NVD · 5
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:microsoft:exchange_server:2013:cumulative_update_23:*:*:*:*:*:* | 2013 cumulative_update_23 | Vulnerable | Microsoft |
| cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_19:*:*:*:*:*:* | 2016 cumulative_update_19 | Vulnerable | Microsoft |
| cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_20:*:*:*:*:*:* | 2016 cumulative_update_20 | Vulnerable | Microsoft |
| cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_8:*:*:*:*:*:* | 2019 cumulative_update_8 | Vulnerable | Microsoft |
| cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_9:*:*:*:*:*:* | 2019 cumulative_update_9 | Vulnerable | Microsoft |
- cpe:2.3:a:microsoft:exchange_server:2013:cumulative_update_23:*:*:*:*:*:* Versions 2013 cumulative_update_23 Vulnerable ·Microsoft
- cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_19:*:*:*:*:*:* Versions 2016 cumulative_update_19 Vulnerable ·Microsoft
- cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_20:*:*:*:*:*:* Versions 2016 cumulative_update_20 Vulnerable ·Microsoft
- cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_8:*:*:*:*:*:* Versions 2019 cumulative_update_8 Vulnerable ·Microsoft
- cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_9:*:*:*:*:*:* Versions 2019 cumulative_update_9 Vulnerable ·Microsoft
Remediation
- Fix · CNA Microsoft Exchange Server 2013 Cumulative Update 23 (Microsoft) Fixed in 15.00.1497.018
- Fix · CNA Microsoft Exchange Server 2019 Cumulative Update 9 (Microsoft) Fixed in 15.02.0858.012
- Fix · CNA Microsoft Exchange Server 2016 Cumulative Update 20 (Microsoft) Fixed in 15.01.2242.010
- Fix · CNA Microsoft Exchange Server 2016 Cumulative Update 19 (Microsoft) Fixed in 15.01.2176.014
- Fix · CNA Microsoft Exchange Server 2019 Cumulative Update 8 (Microsoft) Fixed in 15.02.0792.015
Timeline
- 2021-11-03 Added to CISA KEV
- 2026-10-02 Threatist record created from CVE-2021-31207
- 2026-10-03 Alias added: GHSA-jcxv-6f65-7hrx
References
More Microsoft Exchange Server vulnerabilities
- TI-2024-14170 Microsoft Exchange Server Elevation of Privilege Vulnerability KEVCVSS 3.1CRITICAL 9.8
- TI-2022-19610 Microsoft Exchange Server Elevation of Privilege Vulnerability KEVCVSS 3.1CRITICAL 9.8
- TI-2021-13547 Microsoft Exchange Server Elevation of Privilege Vulnerability KEVCVSS 3.1CRITICAL 9.8
- TI-2021-13502 Microsoft Exchange Server Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8
- TI-2021-08465 Microsoft Exchange Server Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8
- TI-2023-07929 Microsoft Exchange Server Remote Code Execution Vulnerability KEVCVSS 3.1HIGH 8.8
Sources
- CVE-2021-31207 · CVE Program
- CVE-2021-31207 · NVD
- CISA Known Exploited Vulnerabilities
- FIRST EPSS
- GHSA-jcxv-6f65-7hrx · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences