All vulnerabilities
CVE-2021-33766

Microsoft Exchange Server Information Disclosure

Microsoft Exchange ServerApplications & CMS
Open in ThreatlineRecord JSON
CVSS
7.3High
ExploitationExploited in the wildAdded to KEV 18 Jan 2022CISA KEV
Exploit odds (EPSS)98.2%Chance of exploitation activity in the next 30 days, higher than 99.9% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in15.00.1497.015Also 15.01.2176.012, 15.01.2242.008 and 2 moreCVE List
Federal deadline1 Feb 2022Remediation due date for US federal agenciesCISA KEV
CISA required actionApply updates per vendor instructions. CISA KEV

What fixes it

  • 15.00.1497.015Microsoft Exchange Server 2013 Cumulative Update 23CVE List
  • 15.01.2176.012Microsoft Exchange Server 2016 Cumulative Update 19CVE List
  • 15.01.2242.008Microsoft Exchange Server 2016 Cumulative Update 20CVE List
  • 15.02.0792.013Microsoft Exchange Server 2019 Cumulative Update 8CVE List
  • 15.02.0858.010Microsoft Exchange Server 2019 Cumulative Update 9CVE List

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

Timeline

  1. 14 Jul 2021, 17:53 UTCPublishedCVE List
  2. 18 Jan 2022Added to CISA KEVCISA KEV

Public exploit code and templates 1

  • Scanner templateMicrosoft Exchange - Authentication BypassNuclei

Listed so defenders can prioritize. Threatline links to the source and does not host exploit code.

Description

Microsoft Exchange Server contains an information disclosure vulnerability which can allow an unauthenticated attacker to steal email traffic from target.

Text from CVE List

Affected versions 5

  • Microsoft Exchange Server 2013 Cumulative Update 23affected: 15.00.0 before 15.00.1497.015CVE List
  • Microsoft Exchange Server 2016 Cumulative Update 19affected: 15.01.0 before 15.01.2176.012CVE List
  • Microsoft Exchange Server 2016 Cumulative Update 20affected: 15.01.0 before 15.01.2242.008CVE List
  • Microsoft Exchange Server 2019 Cumulative Update 8affected: 15.02.0 before 15.02.0792.013CVE List
  • Microsoft Exchange Server 2019 Cumulative Update 9affected: 15.02.0 before 15.02.0858.010CVE List

References 5