CVE-2021-33766

Microsoft Exchange Server: Information Disclosure

As of , CVE-2021-33766 in Microsoft Exchange Server is on CISA's list of exploited vulnerabilities: CISA listed it on . Our patch-first group: Patch this week.

Exploited
Yes: CISA listed it on 18 January 2022
US federal deadline
1 February 202214 days after CISA listed it. US federal civilian agencies must fix it by then.
Used in ransomware campaigns
Not known to CISA
EPSS score
0.98Higher than 99% of the CVEs EPSS scores. EPSS estimates the chance of exploitation activity in the next 30 days.
EPSS when listed
Not availableCISA listed it before 4 February 2022, where the EPSS files we read begin.
Public exploit
None foundNeither Metasploit nor Exploit-DB lists one.
Fix
No vendor link in CISA's entry

What CISA says to do

Apply updates per vendor instructions.

CISA's required action

What the flaw is

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

CISA's description

Microsoft Exchange Server Information Disclosure Vulnerability

The CVE record's description, from microsoft

CVE published
14 July 2021
Assigned by
microsoft
CVSS
7.3 High (CVSS 3.1, from the CNA)
CWE-287
Improper Authentication
CISA SSVC, exploitation
active
CISA SSVC, automatable
yes
CISA SSVC, technical impact
partial

Timeline

  1. The CVE record was published.
  2. CISA added it to its list of exploited vulnerabilities.
  3. The US federal deadline to fix it.

Exchange Server: other exploited entries

VulnerabilityProductOur groupListedDeadlineEPSS
CVE-2023-21529Deserialization of Untrusted DataMicrosoft Exchange ServerPatch nowRansomware use, listed within a year0.59
CVE-2020-0688Validation Key Remote Code ExecutionMicrosoft Exchange ServerPatch this weekRansomware use; Metasploit module; EPSS 0.99; verified Exploit-DB entry0.99
CVE-2022-41040Server-Side Request ForgeryMicrosoft Exchange ServerPatch this weekRansomware use; Metasploit module; EPSS 0.990.99
CVE-2022-41082Remote Code ExecutionMicrosoft Exchange ServerPatch this weekRansomware use; Metasploit module; EPSS 0.990.99
CVE-2021-26855Remote Code ExecutionMicrosoft Exchange ServerPatch this weekRansomware use; Metasploit module; EPSS 0.990.99
CVE-2021-27065Remote Code ExecutionMicrosoft Exchange ServerPatch this weekRansomware use; Metasploit module; EPSS 0.990.99
CVE-2021-31207Security Feature BypassMicrosoft Exchange ServerPatch this weekRansomware use; Metasploit module; EPSS 0.990.99
CVE-2021-34473Remote Code ExecutionMicrosoft Exchange ServerPatch this weekRansomware use; Metasploit module; EPSS 0.990.99
CVE-2021-34523Privilege EscalationMicrosoft Exchange ServerPatch this weekRansomware use; Metasploit module; EPSS 0.990.99
CVE-2022-41080Privilege EscalationMicrosoft Exchange ServerPatch this weekRansomware use; EPSS 0.770.77

All 17 entries for Exchange Server

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