CVE-2021-31196: Microsoft Exchange Server Information Disclosure Vulnerability
- Is it exploited?
Yes. CISA added it to the Known Exploited Vulnerabilities catalog on , 1,134 days after the CVE record was published.
- How likely is exploitation in the next 30 days?
- 54.1%
EPSS score, percentile 99 of all scored records
- How severe?
- 7.2 High
CVSS v3.1 base score, given by the CNA
- What should I do?
CISA deadline . Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
- Which versions are affected?
Affected
- from 15.00.0 to before 15.00.1497.023
- from 15.01.0 to before 15.01.2242.012
- from 15.01.0 to before 15.01.2308.014
- from 15.02.0 to before 15.02.0922.013
- from 15.02.0 to before 15.02.0858.015
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of ; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of ; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of . About the data.
What to do
Required action, set by CISA
Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
CISA due date for this action: .
Advisories and patches
Linked from CISA's catalog entry
- https://msrc.microsoft.com/update-guide/en-US/advisory/CVE-2021-31196
- https://nvd.nist.gov/vuln/detail/CVE-2021-31196
Affected products and versions
As listed in the CVE record.
| Status | Versions |
|---|---|
| Affected | from 15.00.0 to before 15.00.1497.023 |
| Status | Versions |
|---|---|
| Affected | from 15.01.0 to before 15.01.2242.012 |
| Status | Versions |
|---|---|
| Affected | from 15.01.0 to before 15.01.2308.014 |
| Status | Versions |
|---|---|
| Affected | from 15.02.0 to before 15.02.0922.013 |
| Status | Versions |
|---|---|
| Affected | from 15.02.0 to before 15.02.0858.015 |
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of . About the data.
About this vulnerability
Microsoft Exchange Server contains an information disclosure vulnerability that allows for remote code execution.
Summary: CISA's KEV catalog, as of .
- CISA added CVE-2021-31196 to its Known Exploited Vulnerabilities (KEV) catalog on 21 Aug 2024.
- CISA's ransomware flag for this entry is "Unknown": no evidence of ransomware use in the catalog, which is not proof of none.
- The due date CISA sets for the required action is 11 Sep 2024.
- The CVE record was published on 14 Jul 2021, 1,134 days before it was added to KEV.
- The CVE record carries a CVSS v3.1 base score of 7.2 (High), given by its CNA.
- FIRST's EPSS model puts the probability of exploitation in the next 30 days at 54.1% (percentile 99), as of 28 Oct 2026.
- CISA's SSVC assessment in the CVE record: exploitation active, automatable yes, technical impact total.
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of ; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of ; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of . About the data.
Description
Microsoft Exchange Server Remote Code Execution Vulnerability
Microsoft Exchange Server Remote Code Execution Vulnerability
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of . About the data.
Timeline
| Date | Event |
|---|---|
| CVE record published | |
| Added to CISA KEV | |
| CISA due date for the required action | |
| CVE record last updated |
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