Critical Integer Overflow in Edge Allows PC Takeover — Apply Patch 150.0.4078.48 Now

Microsoft shipped an out-of-band security update for its Edge browser on July 3, 2026, fixing a remote code execution flaw that could give attackers full control of an unpatched system. Tracked as CVE-2026-57974, the vulnerability is rated Important and stems from an integer overflow bug in the Chromium-based browser’s core engine. The company is urging all users to update to Edge version 150.0.4078.48 immediately.

Inside CVE-2026-57974: An Integer Overflow with Dangerous Consequences

The advisory published by Microsoft Security Response Center (MSRC) identifies the vulnerability as an integer overflow. In software, integer overflows occur when an arithmetic operation produces a value that exceeds the maximum limit of the integer type used to store it. When this happens without proper bounds checking, the result wraps around to a small or negative number, which can lead to memory corruption—most commonly a heap buffer overflow. Attackers who successfully exploit such a bug can craft malicious web content that, when rendered by the browser, overwrites critical memory structures and hijacks the process to execute arbitrary code.

Microsoft has withheld the technical specifics of the attack vector, but the consequences of remote code execution (RCE) in a browser are severe. An attacker could install malware, steal sensitive data, or pivot to other devices on the network simply by luring a victim to a booby-trapped webpage or injecting malicious code into a legitimate site. The vulnerability affects all platforms where Edge runs—Windows, macOS, and Linux—because the bug resides in the Chromium rendering engine shared across operating systems.

The company did not disclose whether the flaw is being actively exploited in the wild, nor did it name a reporter. Often, such vulnerabilities are discovered by Google’s Project Zero, third-party security researchers through bug bounty programs, or internal Microsoft teams. Regardless of its provenance, the rapid release of a patch outside of Microsoft’s usual Patch Tuesday cadence signals the seriousness of the issue.

How a Memory Corruption Bug Becomes a Weapon

Integer overflows are a classic category of software security defects, but they remain alarmingly prevalent in large codebases like Chromium. To understand why they’re so dangerous in a browser, consider how modern rendering engines process untrusted input from the web. JavaScript, HTML, CSS, and WebAssembly are all handled by complex parsing and layout routines that involve countless arithmetic operations. A single miscalculation when allocating buffer sizes or computing offsets can open the door to a heap overflow.

In practice, an attacker crafts a web page that triggers the vulnerable code path. The browser’s engine miscomputes a memory allocation, leading to a buffer that is too small for the data being written. The overflow corrupts adjacent memory, which can be manipulated to overwrite function pointers or other control structures. This technique—often combined with other exploits to bypass modern defenses like ASLR and DEP—gives the attacker the ability to redirect execution to shellcode they have placed in memory. From there, the malicious payload runs with the same privileges as the victim user.

For Edge users, the risk is amplified by the browser’s integration with Windows services and Microsoft accounts. A successful RCE could leak cookies, saved passwords, and authentication tokens, allowing the attacker to impersonate the user on online services. In enterprise environments, a compromised browser can become a beachhead for lateral movement across the corporate network.

Who Needs to Act: Every Edge User, Consumer and Enterprise Alike

CVE-2026-57974 affects all versions of Microsoft Edge prior to 150.0.4078.48. That means anyone running the stable channel of Edge on Windows 10, Windows 11, macOS, or Linux should verify their current version and update immediately. Edge on mobile platforms (Android and iOS) uses different underlying engines and is not believed to be affected, though Microsoft has not issued separate guidance for mobile.

Home users who keep automatic updates enabled will likely receive the patch without intervention. However, because this is a critical security fix, performing a manual check ensures it is installed promptly. Enterprise administrators managing fleets of devices should prioritize this update and push it through their standard deployment channels—WSUS, Microsoft Endpoint Manager, or Group Policy—as soon as possible.

The table below summarizes the affected versions and the fixed build:

The Update Itself: What Else Does Version 150.0.4078.48 Bring?

Edge 150.0.4078.48 is a security-focused release that patches CVE-2026-57974. Because Microsoft Edge updates are cumulative, installing this version also includes all previously published security fixes for the browser. The company’s release notes for the stable channel do not mention any new features or functionality changes, indicating that this update is purely a response to the vulnerability.

The update mechanism is straightforward: Edge contacts Microsoft’s servers, downloads the incremental package, and applies it after a browser restart. The patch is typically in the range of a few megabytes. Users can verify the update by navigating to edge://settings/help and confirming the version string.

The Road to Edge 150: Browser Security in the Chromium Era

Microsoft Edge has been built on the open-source Chromium project since January 2020, which means it shares the majority of its code—including the V8 JavaScript engine and the Blink rendering engine—with Google Chrome. While this alignment has dramatically improved compatibility and performance, it also means that vulnerabilities discovered in Chromium often affect both browsers. Microsoft and Google coordinate patching efforts, but each vendor publishes its own advisories and fixes on slightly different schedules.

Historically, integer overflow and related memory safety bugs have plagued Chromium. Google’s Project Zero and external researchers have reported dozens of high-severity overflow flaws over the past several years, many of which were found in image parsing, font handling, and media codecs. The shift to memory-safe languages like Rust has begun in some Chromium components, but the core remains written in C and C++, making these bug classes a persistent threat.

CVE-2026-57974 is notable because it was severe enough to warrant an out-of-band patch from Microsoft. The company typically reserves such urgency for vulnerabilities that are either actively exploited or likely to be exploited soon. While MSRC has not confirmed active attacks, security best practice dictates treating any RCE in a browser as a top-priority fix.

What to Do Right Now: A Step-by-Step Update Guide

Taking action is simple and takes just a few minutes.

For Home Users and Small Businesses

1. Open Microsoft Edge.
2. Click the three-dot menu (top right) and go to Help and feedback > About Microsoft Edge. Alternatively, type edge://settings/help in the address bar.
3. Edge will automatically check for updates. If version 150.0.4078.48 is available, it will begin downloading.
4. Once the download completes, click the Restart button to finish installation.
5. After restart, revisit the About page to confirm the version reads “Microsoft Edge 150.0.4078.48.”

For Enterprise Administrators

• Microsoft Endpoint Manager / Intune: Publish the latest Edge stable channel app as a required update.
• WSUS / Configuration Manager: Synchronize the Edge updates category and approve the 150.0.4078.48 update for deployment.
• Group Policy: If you manage Edge updates via administrative templates, force an update check by setting the “Update policy override” to “Always allow updates” and ensure the update frequency is not blocked.
• Manual verification: On a managed device, run the command msedge.exe --version (Windows) or check the About dialog.

Additional Precautions

• If you cannot immediately update, consider using a different fully patched browser until the update can be applied.
• Be cautious when visiting untrusted websites, and disable JavaScript temporarily as a defense-in-depth measure (though this will break many sites).
• Monitor Microsoft’s Security Update Guide for any revised advisories or additional information about exploit activity.

Outlook: What Comes Next

Microsoft’s quick turnaround on CVE-2026-57974 demonstrates the company’s commitment to Edge security, but the incident is a reminder that browsers remain prime targets for attackers. With the patching now underway, the focus will shift to whether the vulnerability is ever publicly detailed or tied to an exploit kit. Google is expected to release a corresponding Chrome update if the bug originates in shared Chromium code, though no exact date has been announced.

For everyday users, the lesson is simple: reliable automatic updates are the best defense against such threats. Ensure Edge’s background updater is not disabled, and occasionally check for updates manually—especially after a high-profile CVE. Enterprise defenders should audit their update compliance to confirm that all endpoints are running the patched version within the next 24 hours.

As always, staying ahead of browser exploits means keeping software current and practicing smart browsing habits. CVE-2026-57974 may be patched, but it won’t be the last integer overflow to threaten the web.