CVE-2021-31207
Microsoft Exchange Server Security Feature Bypass Vulnerability
KEV RANSOMWAREMEDIUM 6.6EPSS 99.8%
Microsoft Exchange Server Security Feature Bypass Vulnerability
- Affected
- Microsoft · Microsoft Exchange Server 2013 Cumulative Update 23 · Microsoft Exchange Server 2019 Cumulative Update 9 · Microsoft Exchange Server 2016 Cumulative Update 20 · Microsoft Exchange Server 2016 Cumulative Update 19 · Microsoft Exchange Server 2019 Cumulative Update 8
- CVSS v3.1 NVD
- 6.6 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H - CVSS v2.0 NVD
- 6.5 MEDIUM
AV:N/AC:L/Au:S/C:P/I:P/A:P - EPSS
- 99.78% chance of exploitation in the next 30 days, 100th percentile
- CISA KEV
- added 2021-11-03, used in ransomware campaigns
- Published
- 2021-05-11
- Updated
- 2025-10-21
Proof-of-concept exploits (5)
- http://packetstormsecurity.com/files/163895/Microsoft-Exchange-ProxyShell-Remote-Code-Exe…
- aravazhimdr/ProxyShell-POC-Mod6★ · 2021-08-18
- horizon3ai/proxyshell121★ · 2023-08-25
- mithridates1313/ProxyShell_POC16★ · 2021-10-06
- swaptt/swapt-it0★ · 2022-04-10
Metasploit modules (1)
Security advisories
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-31207
- https://www.zerodayinitiative.com/advisories/ZDI-21-819