Cross-Site Scripting (XSS) has been a known vulnerability class for two decades, yet it continues to surface in modern applications, including those built with the latest frameworks and cloud-native architectures. At Microsoft, we still receive a steady stream of XSS reports across our services, from legacy portals to newly deployed single-page apps.

The next chapter of the Microsoft Security Response Center’s (MSRC) BlueHat security conference is fast approaching. BlueHat Asia 2025 will take place in Bengaluru, India, on November 5 – 6, 2025 and the Call for Papers is now open. Submissions will be accepted through September 14, 2025. Now in its third decade, BlueHat is more than a conference, it’s a community.

At Microsoft, securing the ecosystem means more than just fixing bugs—it means proactively hunting for variant classes, identifying systemic weaknesses, and working across teams to protect customers before attackers ever get the chance. This blog highlights one such effort: a deep dive into the risks of misconfigured postMessage handlers across Microsoft services and how MSRC worked with engineering teams to mitigate them.

We’re thrilled to share that this year, the Microsoft Bounty Program has distributed $17 million to 344 security researchers from 59 countries, the highest total bounty awarded in the program’s history. In close collaboration with the Microsoft Security Response Center (MSRC), these security researchers have helped identify and resolve more than a thousand potential vulnerabilities, strengthening protections for Microsoft customers around the world.

Last year, we announced the largest hacking event in history: Zero Day Quest, with up to $4 million in bounty awards. The response from the global security community was incredible and helped improve security for our customers and partners. This year, Zero Day Quest is back with even more potential bounty awards: up to $5 million total for high-impact research in Cloud and AI security.

We’re excited to announce significant updates to the Microsoft .NET Bounty Program. These changes expand the program’s scope, simplify the award structure, and offer great incentives for security researchers. The .NET Bounty Program now offers awards up to $40,000 USD for vulnerabilities impacting the .NET and ASP.NET Core (including Blazor and Aspire).

Summary The growing adoption of large language models (LLMs) in enterprise workflows has introduced a new class of adversarial techniques: indirect prompt injection. Indirect prompt injection can be used against systems that leverage large language models (LLMs) to process untrusted data. Fundamentally, the risk is that an attacker could provide specially crafted data that the LLM misinterprets as instructions.

Revision Change Date 1.0 Information published 07/19/25 2.0 Clarified affected SharePoint product in summary 07/20/25 Added fix availability guidance Provided additional protections guidance regarding: Upgrade SharePoint products to supported versions (if required) Install July 2025 Security Updates Rotate machine keys Updated Microsoft Defender detections and protections section: Documented additional MDE alerts Mapping exposure via Microsoft Defender Vulnerability Management Documented CVE-2025-53771 3.

The Microsoft Researcher Recognition Program offers public thanks and recognition to security researchers who help protect our customers through discovering and sharing security vulnerabilities under Coordinated Vulnerability Disclosure. Today, we are excited to recognize this year’s Most Valuable Researchers (MVRs), based on the total number of points earned for each valid report.

Congratulations to all the researchers recognized in this quarter’s Microsoft Researcher Recognition Program leaderboard! Thank you to everyone for your hard work and continued partnership to secure customers. The top three researchers of the 2025 Q2 Security Researcher Leaderboard are wkai, Brad Schlintz (nmdhkr), and 0x140ce! Check out the full list of researchers recognized this quarter here.

At just 13 years old, Dylan became the youngest security researcher to collaborate with the Microsoft Security Response Center (MSRC). His journey into cybersecurity is inspiring—rooted in curiosity, resilience, and a deep desire to make a difference. Early beginnings: From scratch to security Dylan’s fascination with technology began early. Like many kids, he started with Scratch—a visual programming language for making simple games and animations.

As attackers continue to evolve, Microsoft is committed to staying ahead by not only responding to vulnerabilities, but also by anticipating and mitigating entire classes of threats. One such threat, filesystem redirection attacks, has been a persistent vector for privilege escalation. In response, we’ve developed and deployed a new mitigation in Windows 11 called RedirectionGuard.

Congratulations to all the researchers recognized in this quarter’s Microsoft Researcher Recognition Program leaderboard! Thank you to everyone for your hard work and continued partnership to secure customers. The top three researchers of the 2025 Q1 Security Researcher Leaderboard are 0x140ce, VictorV, Vaisha Bernard of Eye Security! Check out the full list of researchers recognized this quarter here.

This month, the Microsoft Security Response Center recently welcomed some of the world’s most talented security researchers at Microsoft’s Zero Day Quest, the largest live hacking competition of its kind. The inaugural event challenged the security community to focus on the highest-impact security scenarios for Copilot and Cloud with up to $4 million in potential awards.

We are excited to announce the winners of LLMail-Inject, our first Adaptive Prompt Injection Challenge! The challenge ran from December 2024 until February 2025 and was featured as one of the four official competitions of the 3rd IEEE Conference on Secure and Trustworthy Machine Learning (IEEE SaTML). The overall aims of this challenge were to advance the state-of-the-art defenses against indirect prompt injection attacks and to broaden awareness of these new techniques.

Content warning: This blog post contains discussions of sensitive topics. These subjects may be distressing or triggering for some readers. Reader discretion is advised. Today, we are sharing insights on a simple, optimization-free jailbreak method called Context Compliance Attack (CCA), that has proven effective against most leading AI systems. We are disseminating this research to promote awareness and encourage system designers to implement appropriate safeguards.

At Microsoft, we are committed to fostering a secure and innovative environment for our customers and users. As part of this commitment, we are thrilled to announce significant updates to our Copilot (AI) Bounty Program. These changes are designed to enhance the program’s effectiveness, incentivize broader participation, and ensure that our Copilot consumer products remain robust, safe, and secure.

Introduction Microsoft engineering teams use the Security Development Lifecycle to ensure our products are built in alignment with Microsoft’s Secure Future Initiative security principles: Secure by Design, Secure by Default, and Secure Operations. A key component of the Security Development Lifecycle is security testing, which aims to discover and mitigate security vulnerabilities before adversaries can exploit them.

Congratulations to all the researchers recognized in this quarter’s Microsoft Researcher Recognition Program leaderboard! Thank you to everyone for your hard work and continued partnership to secure customers. The top three researchers of the 2024 Q4 Security Researcher Leaderboard are Suresh, VictorV, wkai! Check out the full list of researchers recognized this quarter here.

Introduction In February 2024, we released an update to Exchange Server which contained a security improvement referenced by CVE-2024-21410 that enabled Extended Protection for Authentication (EPA) by default for new and existing installs of Exchange 2019. While we’re currently unaware of any active threat campaigns involving NTLM relaying attacks against Exchange, we have observed threat actors exploiting this vector in the past.

We are excited to introduce LLMail-Inject, a new challenge focused on evaluating state-of-the-art prompt injection defenses in a realistic simulated LLM-integrated email client. In this challenge, participants assume the role of an attacker who sends an email to a user. The user then queries the LLMail service with a question (e.

Our security teams work around the clock to help protect every person and organization on the planet from security threats. We also know that security is a team sport, and that’s why we also partner with the global security community through our bug bounty programs to proactively identify and mitigate potential issues before our customers are impacted.

Welcome to the third installment in our series on transparency at the Microsoft Security Response Center (MSRC). In this ongoing discussion, we talk about our commitment to providing comprehensive vulnerability information to our customers. At MSRC, our mission is to protect our customers, communities, and Microsoft, from current and emerging threats to security and privacy.

Congratulations to all the researchers recognized in this quarter’s Microsoft Researcher Recognition Program leaderboard! Thank you to everyone for your hard work and continued partnership to secure customers. The top three researchers of the 2024 Q3 Security Researcher Leaderboard are wkai, VictorV, and Zhihua Wen! Check out the full list of researchers recognized this quarter here.

34 sessions from 54 presenters representing 20 organizations! We are thrilled to reveal the lineup of speakers and presentations for the 23rd BlueHat Security Conference, in Redmond WA from Oct 29-30. This year’s conference continues the BlueHat ethos and Secure Future Initiative mission of “Security Above All Else”. Security researchers and responders from inside and outside of Microsoft will gather on the Microsoft campus in Redmond, WA to share, debate, and challenge each other, with the shared goal of creating a safer and more secure world for all.

The 23rd edition of Microsoft’s BlueHat security conference will be hosted by the Microsoft Security Response Center (MSRC) at the Redmond, WA corporate campus, October 29 and 30, 2024. BlueHat brings together security researchers and responders from both inside and outside of Microsoft, who come together as peers to exchange ideas, experiences, and best practices, all in the interest of creating a safer and more secure world for everyone.

The Microsoft Researcher Recognition Program offers public thanks and recognition to security researchers who help protect our customers through discovering and sharing security vulnerabilities under Coordinated Vulnerability Disclosure. Today, we are excited to recognize this year’s 100 Most Valuable Researchers (MVRs), based on the total number of points earned for each valid report.

We are excited to announce that this year the Microsoft Bounty Program has awarded $16.6M in bounty awards to 343 security researchers from 55 countries, securing Microsoft customers in partnership with the Microsoft Security Response Center (MSRC). Each year we identify over a thousand potential security issues together, safeguarding our customers from possible threats through the Microsoft Bounty Program.

Microsoft partners with the global security researcher community to surface and report security vulnerabilities to protect all users of Microsoft products and services. Researcher submissions help us address immediate threats while also identifying trends and insights to holistically improve the security of our products and services. We’re always looking for ways to build upon this partnership, and with that goal in mind, we are excited to announce the creation of the MSRC Researcher Resource Center.

Congratulations to all the researchers recognized in this quarter’s Microsoft Researcher Recognition Program leaderboard! Thank you to everyone for your hard work and continued partnership to secure customers. The top three researchers of the 2024 Q2 Security Researcher Leaderboard are Yuki Chen, Lewis Lee & Ver & Zhiniang Peng, and Wei!

At the Microsoft Security Response Center, we are committed to continuously improving the security and performance of our services to meet the evolving needs of our customers. We are excited to announce the rollout of the latest version of our Common Vulnerability Reporting (CVRF) API. This update brings improvements in both security and performance, without requiring any changes to your existing invocation methods.

The Microsoft Security Response Center (MSRC) has always been at the forefront of addressing cyber threats, privacy issues, and abuse arising from Microsoft Online Services. Building on our commitment, we have introduced several updates to the Report Abuse Portal and API, which will significantly improve the way we handle and respond to abuse reports.

Welcome to the second installment in our series on transparency at the Microsoft Security Response Center (MSRC). In this ongoing discussion, we discuss our commitment to provide comprehensive vulnerability information to our customers. At MSRC, our mission is to protect our customers, communities, and Microsoft, from current and emerging threats to security and privacy.

Summary On May 9, 2024, Microsoft successfully addressed multiple vulnerabilities within the Azure Machine Learning (AML) service, which were initially discovered by security research firms Wiz and Tenable. These vulnerabilities, which included Server-Side Request Forgeries (SSRF) and a path traversal vulnerability, posed potential risks for information exposure and service disruption via Denial-of-Service (DOS).

Summary Microsoft Security Response Center (MSRC) was notified in January 2024 by our industry partner, Tenable Inc., about the potential for cross-tenant access to web resources using the service tags feature. Microsoft acknowledged that Tenable provided a valuable contribution to the Azure community by highlighting that it can be easily misunderstood how to use service tags and their intended purpose.

Congratulations to all the researchers recognized in this quarter’s Microsoft Researcher Recognition Program leaderboard! Thank you to everyone for your hard work and continued partnership to secure customers. The top three researchers of the 2024 Q1 Security Researcher Leaderboard are Yuki Chen, VictorV, and Nitesh Surana! Check out the full list of researchers recognized this quarter here.

At the Microsoft Security Response Center (MSRC), our mission is to protect our customers, communities, and Microsoft from current and emerging threats to security and privacy. One way we achieve this is by determining the root cause of security vulnerabilities in Microsoft products and services. We use this information to identify vulnerability trends and provide this data to our Product Engineering teams to enable them to systematically understand and eradicate security risks.

Meet Derrick, a Senior Program Manager on the Operational Threat Intelligence team at Microsoft. Derrick’s role involves understanding and roadmapping the complete set of tools that Threat Intel analysts use to collect, analyze, process, and disseminate threat intelligence across Microsoft. Derrick’s love of learning and his natural curiosity led him to a career in technology and ultimately, to his current role at Microsoft.

This blog provides an update on the nation-state attack that was detected by the Microsoft Security Team on January 12, 2024. As we shared, on January 19, the security team detected this attack on our corporate email systems and immediately activated our response process. The Microsoft Threat Intelligence investigation identified the threat actor as Midnight Blizzard, the Russian state-sponsored actor also known as NOBELIUM.

Faye, a veteran at Microsoft for 22 years, has had a career as varied as it is long. Her journey began in 2002 as the first desktop security Project Manager (PM) in Microsoft IT. From there, she transitioned into owning a deployment team that deployed to desktops and handled operations for Office’s first few customers.

Starting today, we are doubling the maximum bounty award for the Microsoft 365 Insider Bug Bounty Program to $30,000 USD for high impact scenarios, such as unauthenticated non-sandboxed code execution with no user interaction. We are also expanding the scope of our bounty program to include more vulnerability types and products.

As a young boy, Devin found himself captivated by the adventures of Indiana Jones, the whip-wielding archaeologist from the VHS movies his grandfather showed him. The thrill of unearthing history and the allure of the unknown ignited a spark in Devin, leading him to dream of becoming an archaeologist. However, as he grew older and learned more about the realities of archaeology, he realized that his passion lay elsewhere.

Bruce’s story unfolds in Cincinnati, Ohio. As a young boy, he had an ambitious dream of one day becoming the President of the United States. This aspiration remained his guiding star until he began his professional career after college. His mother, amused by his

Today, we are adding a new Security Advisory tab to the Security Update Guide to meet our customers’ needs for a unified and authoritative source for the latest public information about Microsoft security updates and issues. We are continuously listening to feedback from users of the Security Update Guide. Our goal is to find new and improved ways to help customers manage security risks and keep their systems protected.

Congratulations to all the researchers recognized in this quarter’s Microsoft Researcher Recognition Program leaderboard! Thank you to everyone for your hard work and continued partnership to secure customers. The top three researchers of the 2023 Q4 Security Researcher Leaderboard are Yuki Chen, Wei, VictorV! Check out the full list of researchers recognized this quarter here.

The Microsoft security team detected a nation-state attack on our corporate systems on January 12, 2024, and immediately activated our response process to investigate, disrupt malicious activity, mitigate the attack, and deny the threat actor further access. Microsoft has identified the threat actor as Midnight Blizzard, the Russian state-sponsored actor also known as Nobelium.

You asked for it and it’s finally here! The inaugural BlueHat India conference will be held May 16-17th, 2024, in Hyderabad, India! This intimate conference will bring together a unique blend of security researchers and responders, who come together as peers to exchange ideas, experiences, and learnings in the interest of creating a safer and more secure world for all.

28 October 2024 Update Microsoft disabled the ms-appinstaller URI scheme handler by default in App Installer on 28 December 2023 as a security response to protect customers from attackers’ evolving techniques against previous safeguards for CVE-2021-43890. Microsoft is pleased to announce that we have introduced new safeguards to the ms-appinstaller URI scheme handler by default in version 1.

This is the second installment of the Azure Serial Console blog, which provides insights to improve defenders’ preparedness when investigating Azure Serial Console activity on Azure Linux virtual machines. While the first blog post discussed various tracing activities, such as using Azure activity and Sysmon logs on Windows virtual machines to trace serial console activity, this blog outlines how to enable logging for Azure Linux virtual machines using Sysmon for Linux to capture and how to send these events to a log analytics workspace.

We are excited to announce the new Microsoft Defender Bounty Program with awards of up to $20,000 USD. The Microsoft Defender brand encompasses a variety of products and services designed to enhance the security of the Microsoft customer experience. The Microsoft Defender Bounty Program invites researchers across the globe to identify vulnerabilities in Defender products and services and share them with our team.