Skip to content
Fencer Vulns
high 7.8

CVE-2026-21250 json

Windows HTTP.sys Elevation of Privilege Vulnerability

published 2026-02-10 8 mo ago modified 2026-08-19 2 mo ago also EUVD-2026-7321

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.1%
EPSS 1.1% chance of exploitation in 30 days, percentile 65%
public exploits
1
Exploit-DB

Summary

Untrusted pointer dereference in Windows HTTP.sys allows an authorized attacker to elevate privileges locally.

Patch / fix

  • Microsoft Windows 11 Version 24H2 10.0.26100.7840
  • Microsoft Windows 11 Version 25H2 10.0.26200.7840
  • Microsoft Windows 11 version 26H1 10.0.28000.1575
  • Microsoft Windows Server 2022, 23H2 Edition (Server Core installation) 10.0.25398.2149
  • Microsoft Windows Server 2025 10.0.26100.32370
  • Microsoft Windows Server 2025 (Server Core installation) 10.0.26100.32370

Timeline

  1. Published
  2. First public exploit (EDB-52546)

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
8 mo ago

Exploit prediction

1.09% chance of exploitation in the next 30 days, higher than 65% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • EDB-52546 Windows 11 24H2 - Local Privilege Escalation local, 2026-05-04

CVSS scores

assigned by version score vector
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Microsoft Windows 11 Version 24H2
  • Microsoft Windows 11 Version 25H2
  • Microsoft Windows 11 version 26H1
  • Microsoft Windows Server 2022, 23H2 Edition (Server Core installation)
  • Microsoft Windows Server 2025
  • Microsoft Windows Server 2025 (Server Core installation)

Classification

Weakness
  • CWE-822 Untrusted Pointer Dereference

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.