By Adam Barnett, Lead Software Engineer at Rapid7 
Along with Microsoft fixes for 25 non-Microsoft CVEs, that brings the total number of vulnerabilities on the table today to 999.
Whether this is the biggest Patch Tuesday ever depends on how we count, but this is by far the most CVEs that Microsoft has ever published in a single day.
As Rapid7 noted last month, there is no reason to suppose that Patch Tuesday will ever return to the lower volumes we saw prior to 2026. Microsoft is aware of exploitation in the wild for two of the vulnerabilities published today.
The eternal game of elevation of privilege whack-a-mole between Microsoft and attackers continues. This month, the battle is centred on the Windows Advanced Local Procedure Call (ALPC) mechanism, a kernel capability that facilitates inter-process communication. Microsoft is aware of exploitation in the wild already.
Successful abuse of the flaw underlying CVE-2026-85880 grants an attacker SYSTEM via a buffer overflow that enables an out-of-bounds write, and as we all know by now, this is exactly what would happen during the first five minutes of a technically accurate horror movie about ransomware.
We can infer one silver lining here: since neither Server 2025 nor Windows 11 receives patches for CVE-2026-85880, it is likely that Microsoft’s ongoing efforts to level up memory safety by rewriting critical kernel components in Rust are paying off.
Attackers disappointed by Microsoft’s move towards memory safety improvements for various critical kernel components need not leave empty-handed today. Microsoft is aware of existing exploitation in the wild for CVE-2026-81963, an elevation of privilege vulnerability in the Windows Update Stack that leads to SYSTEM privileges via improper link resolution. All supported versions of Windows receive a patch, which presumably tightens up controls to prevent the Windows Update Stack from following a malicious link and overwriting a system component with an attacker-controlled imposter.
The relatively pedestrian CVSS v3 base score of 7.8 is no reason for less concern, since no serious attacker will bother developing an intricate one-shot RCE when a two-stage attack chain consisting of low-privileged local access coupled with elevation of privilege will achieve the same ultimate goal much more easily.
For the second month in a row, Microsoft does not appear to have published any desktop browser security advisories between the start of the month and Patch Tuesday. Microsoft Edge is built on top of Google’s open-source Chromium project, and on September 3, 2026, Google Chrome patched CVE-2026-85046, an exploited-in-the-wild zero-day vulnerability in the V8 JavaScript engine relied upon by both Edge and Chrome.
So, is Microsoft Edge falling dangerously behind Google Chrome? Well, maybe.
In this specific case, the Edge stable channel did receive a patch a day earlier than Chrome on September 2, 2026, and we know this because the Edge release notes mention it. However, almost a week later, Microsoft still hasn’t published a security advisory for CVE-2026-85046, and until that URL returns something better than a 404, that will remain true.
In short: if you’re patched, you are protected, but if you rely on advisories to know which vulns exist, you could miss this zero-day vulnerability altogether. Only Microsoft knows why this advisory is missing, but there is no reason to suppose that Microsoft is somehow immune to the pressures that come along with the vast increase in vulnerability volume. A patch without an advisory is perhaps marginally better than an advisory without a patch, but keeping track of exposures without reliable advisory materials is not straightforward.
Chrome patched 11 other vulnerabilities at the same time as CVE-2026-85046, but it’s not yet clear if those are patched in Edge. Until Microsoft sets the record straight, the only safe assumption is that these vulnerabilities (e.g. CVE-2026-85045) remain unpatched in Edge.
The next Microsoft product lifecycle changes with broad impact occur on October 14, 2026, when Windows 11 24H2 Home & Pro reach end of servicing, and Windows Server 2022 moves to extended support, with free critical security updates continuing, but no further feature development.
At the same time, the final curtain falls for Windows Server 2012 and 2012 R2 with the expiry of the third and final year of cash-for-updates Extended Security Update (ESU) program for these aging workhorses. Office 2021 also moves beyond support, including the Long-Term Servicing Channel, with no ESU available in that case. Also in October, Exchange Server 2016 and 2019 will join the “no ESU” club, after two previous six-month reprieves.
Presumably, Microsoft really means it this time.
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