Microsoft Windows Server 2025 vulnerabilities

CVE-2026-21245 [HIGH] CWE-122 CVE-2026-21245: Heap-based buffer overflow in Windows Kernel allows an authorized attacker to elevate privileges loc Heap-based buffer overflow in Windows Kernel allows an authorized attacker to elevate privileges locally.

CVE-2026-21237 [HIGH] CWE-362 CVE-2026-21237: Concurrent execution using shared resource with improper synchronization ('race condition') in Windo Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Subsystem for Linux allows an authorized attacker to elevate privileges locally.

CVE-2026-21232 [HIGH] CWE-822 CVE-2026-21232: Untrusted pointer dereference in Windows HTTP.sys allows an authorized attacker to elevate privilege Untrusted pointer dereference in Windows HTTP.sys allows an authorized attacker to elevate privileges locally.

CVE-2026-21510 [HIGH] CWE-693 CVE-2026-21510: Protection mechanism failure in Windows Shell allows an unauthorized attacker to bypass a security f Protection mechanism failure in Windows Shell allows an unauthorized attacker to bypass a security feature over a network.

CVE-2026-21240 [HIGH] CWE-367 CVE-2026-21240: Time-of-check time-of-use (toctou) race condition in Windows HTTP.sys allows an authorized attacker Time-of-check time-of-use (toctou) race condition in Windows HTTP.sys allows an authorized attacker to elevate privileges locally.

CVE-2026-21241 [HIGH] CWE-416 CVE-2026-21241: Use after free in Windows Ancillary Function Driver for WinSock allows an authorized attacker to ele Use after free in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.

CVE-2026-20846 [HIGH] CWE-126 CVE-2026-20846: Buffer over-read in Windows GDI+ allows an unauthorized attacker to deny service over a network. Buffer over-read in Windows GDI+ allows an unauthorized attacker to deny service over a network.

CVE-2026-21239 [HIGH] CWE-122 CVE-2026-21239: Heap-based buffer overflow in Windows Kernel allows an authorized attacker to elevate privileges loc Heap-based buffer overflow in Windows Kernel allows an authorized attacker to elevate privileges locally.

CVE-2026-21248 [HIGH] CWE-122 CVE-2026-21248: Heap-based buffer overflow in Windows Hyper-V allows an authorized attacker to execute code locally. Heap-based buffer overflow in Windows Hyper-V allows an authorized attacker to execute code locally.

CVE-2026-21244 [HIGH] CWE-122 CVE-2026-21244: Heap-based buffer overflow in Windows Hyper-V allows an authorized attacker to execute code locally. Heap-based buffer overflow in Windows Hyper-V allows an authorized attacker to execute code locally.

CVE-2026-21513 [HIGH] CWE-693 CVE-2026-21513: Protection mechanism failure in MSHTML Framework allows an unauthorized attacker to bypass a securit Protection mechanism failure in MSHTML Framework allows an unauthorized attacker to bypass a security feature over a network.

CVE-2026-21519 [HIGH] CWE-843 CVE-2026-21519: Access of resource using incompatible type ('type confusion') in Desktop Window Manager allows an au Access of resource using incompatible type ('type confusion') in Desktop Window Manager allows an authorized attacker to elevate privileges locally.

CVE-2026-21508 [HIGH] CWE-287 CVE-2026-21508: Improper authentication in Windows Storage allows an authorized attacker to elevate privileges local Improper authentication in Windows Storage allows an authorized attacker to elevate privileges locally.

CVE-2026-21253 [HIGH] CWE-416 CVE-2026-21253: Use after free in Mailslot File System allows an authorized attacker to elevate privileges locally. Use after free in Mailslot File System allows an authorized attacker to elevate privileges locally.

CVE-2026-21236 [HIGH] CWE-122 CVE-2026-21236: Heap-based buffer overflow in Windows Ancillary Function Driver for WinSock allows an authorized att Heap-based buffer overflow in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.

CVE-2026-21243 [HIGH] CWE-476 CVE-2026-21243: Null pointer dereference in Windows LDAP - Lightweight Directory Access Protocol allows an unauthori Null pointer dereference in Windows LDAP - Lightweight Directory Access Protocol allows an unauthorized attacker to deny service over a network.

CVE-2026-21251 [HIGH] CWE-416 CVE-2026-21251: Use after free in Windows Cluster Client Failover allows an authorized attacker to elevate privilege Use after free in Windows Cluster Client Failover allows an authorized attacker to elevate privileges locally.

CVE-2026-21231 [HIGH] CWE-362 CVE-2026-21231: Concurrent execution using shared resource with improper synchronization ('race condition') in Windo Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Kernel allows an authorized attacker to elevate privileges locally.

CVE-2026-21242 [HIGH] CWE-416 CVE-2026-21242: Use after free in Windows Subsystem for Linux allows an authorized attacker to elevate privileges lo Use after free in Windows Subsystem for Linux allows an authorized attacker to elevate privileges locally.

CVE-2026-21255 [HIGH] CWE-284 CVE-2026-21255: Improper access control in Windows Hyper-V allows an authorized attacker to bypass a security featur Improper access control in Windows Hyper-V allows an authorized attacker to bypass a security feature locally.