CVE-2021-31196
Exploited in the wild. In CISA KEV since 2024‑08‑21. A vendor fix is available.
What to do
The vendor has published a fix. Version details are below where the sources state them.
What it is
From the CVE record
Microsoft Exchange Server Remote Code Execution Vulnerability
In plain language
No plain-language summary for this CVE yet.
Exploitation
Where each signal puts this CVE on the scale from published to confirmed exploited.
- CISA KEV
Listed as exploited in the wild since 2024-08-21.
US federal agencies must remediate by 2024-09-11.
Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
- Public exploits
No public exploit or proof of concept found in the sources we track.
- EPSS
54% chance of exploitation activity in the next 30 days, which ranks it in the 99th percentile of scored CVEs.
Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.
Lifecycle
11 events over 1854 days, from the signal feeds we watch.
- EPSS band changemoderate → highepss band change
- Patch availablerecord updated
- OpenVAS check added
- EPSS band changelow → moderate
- Patch availablerecord updated
- Added to CISA KEV
Affected products
- Microsoft Exchange ServerOperating Systems
- exchange serverOperating Systems / windows
- Microsoft Exchange Server 2013 Cumulative Update 23Enterprise Software / itsm-monitoring
- Microsoft Exchange Server 2016 Cumulative Update 20Enterprise Software / itsm-monitoring
- Microsoft Exchange Server 2016 Cumulative Update 21Enterprise Software / itsm-monitoring
- Microsoft Exchange Server 2019 Cumulative Update 10Enterprise Software / itsm-monitoring
- Microsoft Exchange Server 2019 Cumulative Update 9Enterprise Software / itsm-monitoring
Technical detail
CVSS 3.1 vector
Open in the CVSS calculatorCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
Scored 7.2 by NVD.
How it is reached
- Attack Vector NetworkExploitable remotely over the network without any special conditions
- Attack Complexity LowNo special conditions — the attack can be reliably reproduced
- Privileges Required HighRequires admin or elevated privileges
- User Interaction NoneNo user interaction needed — fully automated exploitation
Scope
- Scope UnchangedImpact is limited to the vulnerable component itself
Impact if exploited
- Confidentiality HighTotal information disclosure — all data in the component is compromised
- Integrity HighTotal loss of integrity — attacker can modify any data in the component
- Availability HighTotal denial of service — the component is completely unavailable
Weaknesses
Sources
References in the record
- cybersecurity-help.cz/vdb/SB2021071319&
- msrc.microsoft.com/update-guide/vulnerability/CVE-2021-31196
- cisa.gov/sites/default/files/csv/known_exploited_vulnerabilities.csv
And 2 more references. See all after sign-in
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