CVE-2026-21525: Microsoft Windows 10 Version 1607 · NULL Pointer Dereference
Affects Microsoft Windows 10 Version 1607Source CVE Database V5
Exploited in the wild · KEV due 3 Mar 2026 · 4% EPSS : upgrade to 10.0.14393.8868 now.
Data as of 26 Oct 2026, 06:26 UTC
- KEV deadline
- US federal agencies must patch by this date; a sensible deadline for everyone else.
- EPSS
- 4.8% chance of exploitation in 30 days – higher than 91% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 10.0.14393.8868, 10.0.17763.8389, 10.0.19044.6937 +10
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:CExploitation evidence
t = 0 is the CVE’s publication on cve.org
Disclosed: evidence found.
CVE published 10 Feb 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: evidence found.
Listed in CISA KEV the same day as disclosure
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
Timeline
CVE ID reserved
by microsoft
, 42 days before disclosure
CVE published
on cve.org
, t = 0
In Threat Radar
record ingested
, 25 minutes after disclosure
Added to CISA KEV (opens in a new tab)
exploitation confirmed
, the same day as disclosure
KEV remediation due
US federal deadline
, 21 days after disclosure
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), CISA KEV (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-26.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| MicrosoftWindows 10 Version 1607 | Affected
| Fixed in
|
| MicrosoftWindows 10 Version 1809 | Affected
| Fixed in
|
| MicrosoftWindows 10 Version 21H2 | Affected
| Fixed in
|
| MicrosoftWindows 10 Version 22H2 | Affected
| Fixed in
|
| MicrosoftWindows 11 version 22H3 | Affected
| Fixed in
|
| MicrosoftWindows 11 Version 23H2 | Affected
| Fixed in
|
| MicrosoftWindows 11 Version 24H2 | Affected
| Fixed in
|
| MicrosoftWindows 11 Version 25H2 | Affected
| Fixed in
|
| MicrosoftWindows 11 version 26H1 | Affected
| Fixed in
|
| MicrosoftWindows 11 Version 26H1 | Affected
| Fixed in
|
| MicrosoftWindows Server 2012 | Affected
| Fixed in
|
| MicrosoftWindows Server 2012 (Server Core installation) | Affected
| Fixed in
|
| MicrosoftWindows Server 2012 R2 | Affected
| Fixed in
|
| MicrosoftWindows Server 2012 R2 (Server Core installation) | Affected
| Fixed in
|
| MicrosoftWindows Server 2016 | Affected
| Fixed in
|
| MicrosoftWindows Server 2016 (Server Core installation) | Affected
| Fixed in
|
| MicrosoftWindows Server 2019 | Affected
| Fixed in
|
| MicrosoftWindows Server 2019 (Server Core installation) | Affected
| Fixed in
|
| MicrosoftWindows Server 2022 | Affected
| Fixed in
|
| MicrosoftWindows Server 2022, 23H2 Edition (Server Core installation) | Affected
| Fixed in
|
| MicrosoftWindows Server 2025 | Affected
| Fixed in
|
| MicrosoftWindows Server 2025 (Server Core installation) | Affected
| Fixed in
|
Description
Null pointer dereference in Windows Remote Access Connection Manager allows an unauthorized attacker to deny service locally.
References
- msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21525 (opens in a new tab)
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-21525 (opens in a new tab)
- vicarius.io/vsociety/posts/cve-2026-21525-detection-script-dos-vulnerability-in-windows-remote-access-connection-manager (opens in a new tab)
- vicarius.io/vsociety/posts/cve-2026-21525-mitigation-script-dos-vulnerability-in-windows-remote-access-connection-manager (opens in a new tab)