CVE-2023-21529
HighExploitedPublic exploitMicrosoft Exchange Server Remote Code Execution Vulnerability
Published Feb 23, 2023 · Updated Aug 19, 2026 · Also known as TR-23-0085
Key Facts
Patch immediately- CVE-2023-21529 is a high-severity vulnerability (CVSS 8.8 v3.1) affecting Exchange Server (Microsoft), Microsoft Exchange Server 2013 Cumulative Update 23, Microsoft Exchange Server 2016 Cumulative Update 23 and 2 more products.
- It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Apr 6, 2026 and is known to be used in ransomware campaigns. Public exploit code is available.
- EPSS estimates a 59% probability of exploitation in the next 30 days.
- Fixed versions are available, including Exchange Server 15.00.1497.047, Exchange Server 15.01.2507.021, Exchange Server 15.02.0986.041.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v3.1
8.8
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS (30-day exploit likelihood)
59%
Higher than 99.1% of all scored CVEs
Exploited in the wild
Yes
4 catalog listings, used by ransomware
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2023-21529 brief as a PDF
Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.
Description
Microsoft Exchange Server Remote Code Execution Vulnerability
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| CISA KEV | Apr 13, 2026 | Apr 27, 2026 | Known |
| Industry KEV feed | Apr 6, 2026 | Apr 27, 2026 | Known |
| CIRCL KEV | Apr 13, 2026 | Apr 27, 2026 | Not reported |
| ENISA EUVD | Apr 13, 2026 | n/a | Not reported |
Required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Affected Products
11 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| Exchange ServerMicrosoft | 2013-cumulative_update_23, 2016-cumulative_update_23, 2019-cumulative_update_11, 2019-cumulative_update_12 | 15.02.0986.041 |
| Microsoft Exchange Server 2013 Cumulative Update 23 | >= 15.00.0 | 15.00.1497.047 |
| Microsoft Exchange Server 2016 Cumulative Update 23 | >= 15.01.0 | 15.01.2507.021 |
| Microsoft Exchange Server 2019 Cumulative Update 11 | >= 15.02.0 | 15.02.0986.041 |
| Microsoft Exchange Server 2019 Cumulative Update 12 | >= 15.02.0 | 15.02.1118.025 |
Patched Releases
Exchange Server
15.00.1497.047, 15.01.2507.021, 15.02.0986.041, 15.02.1118.025
Microsoft Exchange Server 2013 Cumulative Update 23
15.00.1497.047
Microsoft Exchange Server 2016 Cumulative Update 23
15.01.2507.021
Microsoft Exchange Server 2019 Cumulative Update 11
15.02.0986.041
Microsoft Exchange Server 2019 Cumulative Update 12
15.02.1118.025
Timeline
Publicly disclosed
Feb 23, 2023
Added to Industry KEV feed
Apr 6, 2026
Added to CISA KEV
Apr 13, 2026
Added to CIRCL KEV
Apr 13, 2026
Added to ENISA EUVD
Apr 13, 2026
Last updated
Aug 19, 2026
Weakness Type
- CWE-502 Deserialization of Untrusted Data
References
- advisoryhttps://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-0767
- advisoryhttps://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-25728
- advisoryhttps://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-25729
- advisoryhttps://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-25730
- advisoryhttps://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-25732
FAQ
Common Questions.
Microsoft Exchange Server Remote Code Execution Vulnerability
Affected: Exchange Server (Microsoft) versions 2013-cumulative_update_23, 2016-cumulative_update_23, 2019-cumulative_update_11, 2019-cumulative_update_12; Microsoft Exchange Server 2013 Cumulative Update 23 versions >= 15.00.0; Microsoft Exchange Server 2016 Cumulative Update 23 versions >= 15.01.0, among others. The full list is in the CVE brief.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Apr 6, 2026 and is known to be used in ransomware campaigns.
Yes. It was added on Apr 13, 2026 with a federal remediation due date of Apr 27, 2026.
Public exploit code is available.
Fixed versions are available, including Exchange Server 15.00.1497.047, Exchange Server 15.01.2507.021, Exchange Server 15.02.0986.041.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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