Windows 11 Falls to Three New Zero-Day Exploits on First Day of Pwn2Own Berlin 2025

Windows 11 endured a tough opening day at the Pwn2Own Berlin 2025 security contest, as researchers uncovered three separate zero-day vulnerabilities that enabled privilege-escalation all the way to SYSTEM level—the highest tier of Windows authority and a potential stepping-stone to full device compromise.

A Trio of Successful Breaches

1. STARLabs SG researcher Chen Le Qi combined a use-after-free flaw with an integer-overflow bug, earning a $30 000 reward.

2. Independent researcher Marcin Wiązowski leveraged an out-of-bounds memory-write vulnerability to achieve the same SYSTEM-level access, also netting $30 000.

3. Out Of Bounds’ Hyeonjin Choi exploited a type-confusion weakness, securing a $15 000 payout.

All three exploits bypassed Windows 11’s existing mitigation layers under the event’s strict time limits, underscoring the persistent value of in-depth vulnerability research.

How Pwn2Own Works

Organised by Trend Micro’s Zero Day Initiative, Pwn2Own is a twice-yearly competitive bug-bounty event that invites elite “white-hat” hackers to find and weaponise previously unknown vulnerabilities. Successful demonstrations earn cash prizes and—crucially—the affected vendors receive technical details privately, allowing patches to be developed before criminal actors can replicate the attacks. The Berlin 2025 edition features targets ranging from operating systems and smartphones to automotive technologies.

Implications for Microsoft and Users

Although Microsoft has not yet issued a public statement, the company will receive the exploit proofs of concept under ZDI’s coordinated-disclosure rules. Patch timelines vary, but security updates for Windows frequently arrive on the second Tuesday of each month (“Patch Tuesday”). Until fixes are released, administrators are advised to:

• Enable automatic updates on Windows 11 systems to ensure patches are applied as soon as they appear.

• Limit local administrator privileges, reducing the blast radius if privilege-escalation flaws are exploited.

• Monitor vendor advisories and threat-intelligence feeds for interim mitigation guidance.

A Reminder of Responsible Hacking’s Value

Pwn2Own’s opening-day results illustrate why manufacturers encourage responsible disclosure: paying researchers tens of thousands of dollars is a modest price compared with the potential fallout from unpatched zero-days circulating on the black market. With more competition rounds scheduled this week—including categories for virtualisation software and enterprise applications—additional vulnerabilities are likely to surface before the Berlin conference closes.

For Windows 11 users, the message is clear: stay current on updates, enforce least-privilege principles and follow official security advisories. For the wider industry, Pwn2Own continues to prove that collaboration between vendors and researchers is one of the most effective defences against the ever-evolving threat landscape.

Photo Credit: DepositPhotos.com