01 Record
CVE-2021-33766
Microsoft Exchange Server Information Disclosure Vulnerability
HighKEVPUBLISHEDCNA: microsoft
CNA base score7.3 CVSS v3.xCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L/E:U/RL:O/RC:C
02 Description
Microsoft Exchange Server Information Disclosure Vulnerability
03 Exploitation and scoring
- Exploitation
- Exploited in the wild. Listed in the CISA Known Exploited Vulnerabilities catalog on 2022-01-18. Federal remediation due 2022-02-01.
- SSVC decision
- ExploitationactiveCISA reports credible evidence of active exploitation.
- AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
- Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.
- EPSS probability
- 98.17% probability of exploitation activity in the next 30 days.
- EPSS percentile
- Equal to or higher than the score of 99.9% of scored records. A rank, not a probability.
- NVD base score
- 7.3 (CVSS v3.x), scored by the NVD independently of the CNA.
- NVD CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
- NVD analysis status
- Analyzed. NVD last modified this record on 2026-08-10.
- Red Hat severity
- No Red Hat rating. Red Hat rates the CVEs that affect its products.
Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.
04 Metadata
- Published
- 2021-07-14 17:53Z5 YR AGO
- Last updated
- 2026-08-10 15:11Z2 MO AGO
- Reserved
- 2021-05-28
- Assigning CNA
- microsoft
- Record state
- PUBLISHED
- Severity
- High (CVSS 7.3)
- CNA CVSS 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
- Weaknesses
- No CWE assigned
- Data version
- 5.2
- Document digest
- fc7a8bbf0af3aa2ed65562ba0f3910789482d477320f5afa119170d470864f17
05 Affected products
VendorProductVersionsPlatforms
MicrosoftMicrosoft Exchange Server 2013 Cumulative Update 2315.00.0 to < 15.00.1497.015x64-based Systems
MicrosoftMicrosoft Exchange Server 2016 Cumulative Update 1915.01.0 to < 15.01.2176.012x64-based Systems
MicrosoftMicrosoft Exchange Server 2016 Cumulative Update 2015.01.0 to < 15.01.2242.008x64-based Systems
MicrosoftMicrosoft Exchange Server 2019 Cumulative Update 815.02.0 to < 15.02.0792.013x64-based Systems
MicrosoftMicrosoft Exchange Server 2019 Cumulative Update 915.02.0 to < 15.02.0858.010x64-based Systems
06 References
- msrc.microsoft.comMicrosoft Exchange Server Information Disclosure Vulnerabilityhttps://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-33766
- portal.msrc.microsoft.comhttps://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-33766
- www.zerodayinitiative.comhttps://www.zerodayinitiative.com/advisories/ZDI-21-798/
- www.cisa.govhttps://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-33766