CVE-2026-21248
Heap-based buffer overflow in Windows Hyper-V allows an authorized attacker to execute code locally.
Does this matter?
A public exploit is published in Exploit-DB and the impact is high, while EPSS rates exploitation at 1.3%. Anyone can run this; patch or mitigate before the next change window and check exposed instances for signs of use.
Description
Heap-based buffer overflow in Windows Hyper-V allows an authorized attacker to execute code locally.
- CVSS 3.1
- 7.3 HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H
- EPSS
- 1.33% probability · 71th percentile
- Public exploits
- 1 in Exploit-DB · first 30 April 2026
- CISA KEV
- Not listed
- Weakness
- CWE-122, CWE-787
- Affected
- microsoft/windows 10 1607 · microsoft/windows 10 1809 · microsoft/windows 10 21h2 · microsoft/windows 10 22h2 · microsoft/windows 11 23h2 · microsoft/windows 11 24h2 · microsoft/windows 11 25h2 · microsoft/windows server 2016 · microsoft/windows server 2019 · microsoft/windows server 2022 · microsoft/windows server 2022 23h2 · microsoft/windows server 2025
- Source
- secure@microsoft.com
EPSS 1.3% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
Public exploits (1)
Entries in Exploit-DB that cite this CVE. Links go to the Exploit-DB page and to the file in the public repository; nothing is hosted here. A verified tick means the Exploit-DB team confirmed the exploit works against the stated version.
References
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.