CVE-2026-40405 | Windows TCP/IP Denial of Service Vulnerability

Null pointer dereference in Windows TCP/IP allows an unauthorized attacker to deny service over a network.

Published: 2026-05-12 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-40405 is rated Moderate Risk (52.1/100): CVSS High severity, with medium exploitation likelihood (EPSS 1.08%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-40405

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.17% 1.08% +0.91%
2 2026-06-13 0.15% 0.17% +0.02%
3 2026-05-18 — 0.15% —

Full EPSS history (5 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-40405

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]

Weakness enumeration for CVE-2026-40405

GitHub Security Advisory for CVE-2026-40405

GHSA-mj3g-9j9x-c556 · Severity: high — Null pointer dereference in Windows TCP/IP allows an unauthorized attacker to deny service over a...

Affected software / configurations for CVE-2026-40405

Vendor Product Version Raw CPE
microsoft windows_11_24h2 < 10.0.26100.8390 cpe:2.3:o:microsoft:windows_11_24h2:*:*:*:*:*:*:arm64:*
microsoft windows_11_24h2 < 10.0.26100.8390 cpe:2.3:o:microsoft:windows_11_24h2:*:*:*:*:*:*:x64:*
microsoft windows_11_25h2 < 10.0.26200.8390 cpe:2.3:o:microsoft:windows_11_25h2:*:*:*:*:*:*:arm64:*
microsoft windows_11_25h2 < 10.0.26200.8390 cpe:2.3:o:microsoft:windows_11_25h2:*:*:*:*:*:*:x64:*
microsoft windows_11_26h1 < 10.0.28000.2113 cpe:2.3:o:microsoft:windows_11_26h1:*:*:*:*:*:*:arm64:*
microsoft windows_11_26h1 < 10.0.28000.2113 cpe:2.3:o:microsoft:windows_11_26h1:*:*:*:*:*:*:x64:*
microsoft windows_server_2025 < 10.0.26100.32772 cpe:2.3:o:microsoft:windows_server_2025:*:*:*:*:*:*:*:*

References for CVE-2026-40405

cvelogic Threat Intelligence