CVE-2021-34523
What it is
Microsoft Exchange Server Elevation of Privilege Vulnerability
At a glance
- Exploitability
- Can be exploited locally on the machine without logging in. High risk of data exposure, data tampering.
- In the wild
- CISA lists this as exploited in real attacks. Treat as urgent.
- Fix
- A patch, advisory or fixed version is referenced. Upgrade or apply it.
Timeline
- ReservedThe CVE id was reserved by its CNA
- PublishedDisclosed publicly on CVE.org and NVD
- 2021-11-03 Exploited in the wildAdded to CISA's Known Exploited Vulnerabilities list
- 2021-11-17 Remediation deadlineCISA's due date for federal agencies to fix it
- Last updatedMost recent change to the record
Why it ranks here
- Exploited in the wild: yes, CISA lists it. This puts it above everything that is not.
- Exploit odds: 100.0% in the next 30 days (EPSS).
- Severity: 9.0 CRITICAL (CVSS).
- Fix: a patch or advisory is linked.
- It meets the bar for Drop everything: critical, and exploited or very likely to be.
Details
- Published
- Last modified
- Added to CISA KEV
- 2021-11-03
- Exploit probability
- 100.0% · EPSS, next 30 days
- Record status
- Analyzed
Affected
- Microsoft Exchange Server 2013
- Microsoft Exchange Server 2016
- Microsoft Exchange Server 2019
Attack profile CVSS 3.1 · 9.0
- Attack vector
- Local
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
- Scope
- Changed
- Confidentiality
- High
- Integrity
- High
- Availability
- None
Raw vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N
Is it in your code?
Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.
Read https://cve-list.com/agent/cve/CVE-2021-34523.md and follow it. Check whether this project is affected by CVE-2021-34523. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.
Fix and advisories
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-34523
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34523
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-34523
- http://packetstormsecurity.com/files/163895/Microsoft-Exchange-ProxyShell-Remote-Code-Execution.html
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34523
- https://www.zerodayinitiative.com/advisories/ZDI-21-822/
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-34523