Vulnerability in Microsoft Exchange Server 2013 Cumulative Update 23
CVE-2021-33766
Microsoft Exchange Server Information Disclosure Vulnerability
EPSS: 0.938 (99.9th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 7.3 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L/E:U/RL:O/RC:C.
Affected products
- Microsoft Exchange Server 2013 Cumulative Update 23 — versions 15.00.0
- Microsoft Exchange Server 2016 Cumulative Update 19 — versions 15.01.0
- Microsoft Exchange Server 2016 Cumulative Update 20 — versions 15.01.0
- Microsoft Exchange Server 2019 Cumulative Update 8 — versions 15.02.0
- Microsoft Exchange Server 2019 Cumulative Update 9 — versions 15.02.0
CISA KEV (Known Exploited Vulnerabilities)
This CVE is on the CISA KEV catalog, added on . CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.
BOD 22-01 due date: .
Required action: Apply updates per vendor instructions.
Public proof-of-concept exploits
References
- portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-33766 (x_refsource_MISC)
- www.zerodayinitiative.com/advisories/ZDI-21-798/ (x_refsource_MISC)
Frequently asked questions
- What is CVE-2021-33766?
- CVE-2021-33766 is a high-severity vulnerability in Microsoft Exchange Server 2013 Cumulative Update 23. CVSS score: 7.3/10. Published 2021-07-14.
- How severe is CVE-2021-33766?
- High severity. CVSS v3 base score is 7.3 out of 10.
- Is CVE-2021-33766 known to be exploited?
- Yes. CVE-2021-33766 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2022-01-18), indicating it is being actively exploited. 19 public proof-of-concept repositories are indexed.