Reported by 3 outlets

Timeline

1. original reporting

   HardBreacher Exploit Targets Kaspersky Endpoint Security Zero-Day for Windows 11 Privilege Escalation

   gbhackers.com · 43d ago · August 31st, 2026

   A proof of concept called HardBreacher allegedly exploits an unpatched local privilege escalation flaw in Kaspersky Antivirus for Endpoint. This vulnerability allows a local user to control a privileged component. The code was published by a GitHub user named MSNightmare and is being presented as a zero-day vulnerability. However, the vendor has not confirmed it. […] The post HardBreacher Exploit Targets Kaspersky Endpoint Security Zero-Day for Windows 11 Privilege Escalation appeared first on GBHackers Security | #1 Globally Trusted Cyber Security News Platform .

2. update from cyberpress.org

   HardBreacher PoC Targets Kaspersky Endpoint Security Zero-Day for Windows 11 Privilege Escalation

   cyberpress.org · 43d ago · August 31st, 2026

   A publicly available proof-of-concept (PoC) named HardBreacher claims to exploit an unpatched elevation-of-privilege issue in Kaspersky Endpoint Security for Windows, potentially allowing a local user to gain high-level access on affected Windows 11 systems. Documented by GitHub user MSNightmare, also known as Nightmare Eclipse, and should be treated as an unverified but high-priority enterprise security exposure pending vendor confirmation. The HardBreacher repository describes the issue as a “Kaspersky Antivirus For Endpoint ZeroDay Elevation of Privileges Vulnerability.” HardBreacher PoC Targets Kaspersky Endpoint Security Zero-Day According to the project documentation, the researcher tested the PoC against a fully patched Windows 11 25H2 environment running Kaspersky for Endpoint version 14.0.0.504. The claimed weakness is local rather than remote. An attacker would first need code execution or an existing foothold on a targeted device, such as through malware, stolen user credentials, a malicious software installer, or abuse of another vulnerability. If exploitation succeeds, the local user could reportedly gain permissions that are normally unavailable to that account, thereby converting an initial low-privilege compromise into a far more serious system-level incident. The publication is especially notable because endpoint security products commonly run with extensive operating-system privileges and interact closely with protected files, processes, services, and user-i

3. mentioned by securityweek.com

   Nightmare Eclipse Drops ‘HardBreacher’ Kaspersky Product Exploit

   securityweek.com · 43d ago · August 31st, 2026