CVE-2021-26858
Act now ● On CISA KEV — actively exploited used in ransomware
Actively exploited — on the CISA KEV list.
CVSS base
7.8
HIGH
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
EPSS — probability of exploitation (30 days)
93.7%
99.8th percentile
CISA KEV
Listed
Added 2021-11-03 · patch by 2022-05-03
Weakness / dates
—
Published 2021-03-03 · modified 2026-08-19
CVSS breakdown
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
| Attack Vector | L | Local |
| Attack Complexity | L | Low |
| Privileges Required | N | None |
| User Interaction | R | Required |
| Scope | U | Unchanged |
| Confidentiality | H | High |
| Integrity | H | High |
| Availability | H | High |
Timeline
- 2021-03-03 — Published (NVD)
- 2021-11-03 — Added to CISA KEV (actively exploited)
- 2022-05-03 — CISA patch-by deadline
- 2026-08-19 — Last modified (NVD)
Description
Microsoft Exchange Server Remote Code Execution Vulnerability