Actively exploited · Published Jul 14, 2021 · Assigned by microsoft
CVE-2021-33766Microsoft Exchange Server Information Disclosure Vulnerability
High 7.3 Exploited
In plain English
A high-severity security flaw in Microsoft Exchange Server 2013 Cumulative Update 23 from Microsoft. Attackers are actively exploiting it in the wild (listed by CISA on January 18, 2022). The chance it is exploited in the next 30 days is estimated at 98.2% (higher than 99.9% of all known vulnerabilities). Ready-made attack tooling exists: Nuclei, public proof-of-concept code. Apply updates per vendor instructions.
Severity (CVSS 3.1)7.3High
Exploit odds (30 days)98.2%top 0.1% of all CVEs
Exploited in the wildYesCISA KEV since Jan 18, 2022
Attack tooling2Nuclei, Public PoC
CISA guidance
Apply updates per vendor instructions.
Federal agencies must remediate by Feb 1, 2022.
Official description
Microsoft Exchange Server Information Disclosure Vulnerability
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Microsoft | Microsoft Exchange Server 2013 Cumulative Update 23 | 15.00.0 – before 15.00.1497.015 |
| Microsoft | Microsoft Exchange Server 2016 Cumulative Update 19 | 15.01.0 – before 15.01.2176.012 |
| Microsoft | Microsoft Exchange Server 2016 Cumulative Update 20 | 15.01.0 – before 15.01.2242.008 |
| Microsoft | Microsoft Exchange Server 2019 Cumulative Update 8 | 15.02.0 – before 15.02.0792.013 |
| Microsoft | Microsoft Exchange Server 2019 Cumulative Update 9 | 15.02.0 – before 15.02.0858.010 |
References
- Microsoft Exchange Server Information Disclosure Vulnerability vendor-advisory, patch
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-33766 x_refsource_MISC, x_transferred
- https://www.zerodayinitiative.com/advisories/ZDI-21-798/ x_refsource_MISC, x_transferred
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-33766 government-resource