PT-2026-40162 · Microsoft · Windows Application Identity Subsystem+1

CVE-2026-34343 · Published 2026-05-12 · Updated 2026-05-12

Positive Technologies (AI Summary)

CVSS v3.1

7.8

High

Base vector

AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Name of the Vulnerable Software and Affected Versions Windows Application Identity (AppID) Subsystem (affected versions not specified)

Description A heap-based buffer overflow in the Windows Application Identity (AppID) Subsystem allows an authorized attacker to elevate privileges locally to SYSTEM. A heap overflow occurs when a program writes more data to a heap-allocated memory block than it can hold, potentially allowing the execution of arbitrary code.

Recommendations Apply the patch released on May 12.

Fix

Heap Based Buffer Overflow

Weakness Enumeration

CWE-122

Related Identifiers

BDU:2026-06735

CVE-2026-34343

Affected Products

Windows

Windows Application Identity Subsystem

References · 6

• https://nvd.nist.gov/vuln/detail/CVE-2026-34343 · Security Note
• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-34343 · Vendor Advisory
• https://bdu.fstec.ru/vul/2026-06735 · Security Note
• http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-34343 · Security Note
• https://msrc.microsoft.com/update-guide/en-US/advisory/CVE-2026-34343 · Vendor Advisory
• https://twitter.com/windowsforum/status/2054266210510950803 · Twitter Post