CVE-2021-26412

Exploitation

Public exploit code exists. CISA's assessment records a public proof of concept. That is not a report of exploitation in the wild.

SSVC decision

• ExploitationpocPublic proof-of-concept exploit code exists. Not a report of exploitation in the wild.
• AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
• Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.

CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.

EPSS probability

32.98% probability of exploitation activity in the next 30 days.

EPSS percentile

Ranks above 98.2% of scored records. A rank, not a probability.

NVD base score

9.1 (CVSS v3.x), scored by the NVD independently of the CNA.

NVD CVSS vector

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

NVD analysis status

Modified. NVD last modified this record on 2026-08-19.

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.

Published

2021-03-02 23:55Z5 YR AGO

Last updated

2026-08-19 16:30Z16 DAYS AGO

Reserved

2021-01-29

Assigning CNA

microsoft

Record state

PUBLISHED

Severity

Critical (CVSS 9.1)

CNA CVSS vector

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H/E:P/RL:O/RC:C

Weaknesses

No CWE assigned

Data version

5.2

Document digest

0896c49cfa103941a2629935802b0241bd028036e4867727e689727499a91e66

• msrc.microsoft.comMicrosoft Exchange Server Remote Code Execution Vulnerabilityhttps://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-26412vendor-advisorypatch
• portal.msrc.microsoft.comhttps://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26412x_refsource_MISC