CVE-2026-62913ImportantRevised 13 Aug
Microsoft Exchange Server Remote Code Execution Vulnerability
Assessment
Heap-based buffer overflow in Microsoft Exchange Server allows an authorized attacker to execute code over a network.
- Severity
- Important
- CVSS base score
- 8.8CVSS:3.1/
AV:N/ AC:L/ PR:L/ UI:N/ S:U/ C:H/ I:H/ A:H/ E:U/ RL:O/ RC:C - Impact
- Remote Code Execution
- EPSS, next 30 days
- 0.9%Higher than 58.5% of scored CVEs · FIRST model run 26 Sep 2026 · about EPSS
- Exploitability
- Exploitation Less Likely
- Publicly disclosed
- No
- Customer action
- Required: apply the update
- Component
- Microsoft Exchange Server
- Weakness
- CWE-122: Heap-based Buffer Overflow
- Issued by
- Microsoft
- Published
- 11 Aug 2026 · August 2026
- Last revised
- 13 Aug 2026Added acknowledgements. This is an informational change only.
Updates that fix it
4 KBs| KB | Type | Restart | Applies to | Other CVEs |
|---|---|---|---|---|
| KB5121573 | Security Update | Required | Microsoft Exchange Server Subscription Edition RTM | All CVEs in KB5121573 |
| KB5121574 | Security Update | Required | Microsoft Exchange Server 2019 Cumulative Update 15 | All CVEs in KB5121574 |
| KB5121575 | Security Update | Required | Microsoft Exchange Server 2019 Cumulative Update 14 | All CVEs in KB5121575 |
| KB5121576 | Security Update | Required | Microsoft Exchange Server 2016 Cumulative Update 23 | All CVEs in KB5121576 |
Affected products
ESU, Server Software4 affected products
- Microsoft Exchange Server 2016 Cumulative Update 23
- Microsoft Exchange Server 2019 Cumulative Update 14
- Microsoft Exchange Server 2019 Cumulative Update 15
- Microsoft Exchange Server Subscription Edition RTM