Microsoft's May 2017 Patch Tuesday fixes 57 vulnerabilities across Windows, Browser and System Center - 14 rated Critical, 2 publicly disclosed before the patch shipped, 4 already exploited in the wild. Patch CVE-2017-0222 first.
Why this number differs from other roundups. Microsoft's May 2017 release document lists 77 entries. 11 are Azure Linux (Mariner) OS package updates and 9 are republished Chromium fixes for Edge - neither is a Microsoft product vulnerability. The 57 above is the real Patch Tuesday set. See the breakdown →
Ranked by exploitation reality, not score alone. This month's exploited flaw is rated Critical - a severity-sorted list would bury it.
Patch today
Confirmed attacks are already happening. Emergency change window.
CVE-2017-0222Internet Explorer Memory Corruption VulnerabilityCVE-2017-0263Win32k Elevation of Privilege VulnerabilityCVE-2017-0261Microsoft Office Remote Code Execution VulnerabilityCVE-2017-0262Microsoft Office Remote Code Execution VulnerabilityPatch this week
Details are already public. Working exploits typically follow within days.
CVE-2017-0064Internet Explorer Security Feature Bypass VulnerabilityCVE-2017-0229Scripting Engine Memory Corruption VulnerabilityPatch this cycle
No known exploitation yet, but network-reachable and high impact.
CVE-2017-0223Scripting Engine Memory Corruption VulnerabilityCVE-2017-0235Scripting Engine Memory Corruption VulnerabilityCVE-2017-0236Scripting Engine Memory Corruption VulnerabilitySee all 14 Critical →Most roundups quote a single number. These are three unrelated release streams.
Microsoft channel only · 57 CVEs
| Critical | 14 |
|---|---|
| Important | 43 |
| Moderate | 0 |
| Low | 0 |
What an attacker gains if it works
| Remote Code Execution | 24 |
|---|---|
| Information Disclosure | 14 |
| Denial of Service | 9 |
| Elevation of Privilege | 8 |
| Security Feature Bypass | 2 |
Where this month’s fixes concentrate - filter by any of them in the table below
Sorted by risk by default: exploited first, then publicly disclosed, then severity, then CVSS. Search by CVE, title, component or KB number.
| Title | Status | KB | |||||
|---|---|---|---|---|---|---|---|
| Critical | CVE-2017-0222 | Internet Explorer Memory Corruption Vulnerability | RCE | 7.1 | Exploited | Internet Explorer | 4016871 +7 |
| Important | CVE-2017-0263 | Win32k Elevation of Privilege Vulnerability | EoP | 7.8 | Exploited | Windows Kernel-Mode Drivers | 4016871 +10 |
| Important | CVE-2017-0261 | Microsoft Office Remote Code Execution Vulnerability | RCE | - | Exploited | Microsoft Office | 3114375 +2 |
| Important | CVE-2017-0262 | Microsoft Office Remote Code Execution Vulnerability | RCE | - | Exploited | Microsoft Office | 3114375 +2 |
| Important | CVE-2017-0064 | Internet Explorer Security Feature Bypass Vulnerability | Bypass | 4.3 | Disclosed | Internet Explorer | 4016871 +7 |
| Critical | CVE-2017-0229 | Scripting Engine Memory Corruption Vulnerability | RCE | 4.2 | Disclosed | Microsoft Scripting Engine | 4016871 +3 |
| Critical | CVE-2017-0223 | Scripting Engine Memory Corruption Vulnerability | RCE | 4.2 | More likely | Microsoft Scripting Engine | 4016871 |
| Critical | CVE-2017-0235 | Scripting Engine Memory Corruption Vulnerability | RCE | 4.2 | More likely | Microsoft Scripting Engine | 4016871 |
| Critical | CVE-2017-0236 | Scripting Engine Memory Corruption Vulnerability | RCE | 4.2 | More likely | Microsoft Scripting Engine | 4016871 +3 |
| Important | CVE-2017-0077 | Dxgkrnl.sys Elevation of Privilege Vulnerability | EoP | 7.8 | More likely | Microsoft Graphics Component | 4016871 +10 |
| Important | CVE-2017-0226 | Internet Explorer Memory Corruption Vulnerability | RCE | 7.5 | More likely | Internet Explorer | 4016871 +6 |
| Important | CVE-2017-0238 | Microsoft Edge Memory Corruption Vulnerability | RCE | 7.5 | More likely | Microsoft Scripting Engine | 4016871 +6 |
| Important | CVE-2017-0213 | Windows COM Elevation of Privilege Vulnerability | EoP | 6.7 | More likely | Windows COM | 4018556 +10 |
| Important | CVE-2017-0214 | Windows COM Elevation of Privilege Vulnerability | EoP | 6.7 | More likely | Windows COM | 4016871 +10 |
| Important | CVE-2017-0230 | Scripting Engine Memory Corruption Vulnerability | RCE | 4.2 | More likely | Microsoft Scripting Engine | 4016871 +1 |
| Important | CVE-2017-0234 | Scripting Engine Memory Corruption Vulnerability | RCE | 4.2 | More likely | Microsoft Scripting Engine | 4016871 +3 |
| Critical | CVE-2017-0272 | Windows SMB Remote Code Execution Vulnerability | RCE | 8.1 | — | Windows SMB Server | 4016871 +10 |
| Critical | CVE-2017-0277 | Windows SMB Remote Code Execution Vulnerability | RCE | 7.0 | — | Windows SMB Server | 4016871 +10 |
| Critical | CVE-2017-0278 | Windows SMB Remote Code Execution Vulnerability | RCE | 7.0 | — | Windows SMB Server | 4016871 +10 |
| Critical | CVE-2017-0279 | Windows SMB Remote Code Execution Vulnerability | RCE | 7.0 | — | Windows SMB Server | 4016871 +10 |
| Critical | CVE-2017-0290 | Microsoft Malware Protection Engine Remote Code Execution Vulnerability | RCE | - | — | Microsoft Malware Protection Engine | — |
| Critical | CVE-2017-8538 | Microsoft Malware Protection Engine Remote Code Execution Vulnerability | RCE | - | — | Microsoft Malware Protection Engine | — |
| Critical | CVE-2017-8540 | Microsoft Malware Protection Engine Remote Code Execution Vulnerability | RCE | - | — | Microsoft Malware Protection Engine | — |
| Critical | CVE-2017-8541 | Microsoft Malware Protection Engine Remote Code Execution Vulnerability | RCE | - | — | Microsoft Malware Protection Engine | — |
| Important | CVE-2017-0273 | Windows SMB Denial of Service Vulnerability | DoS | 8.1 | — | Windows SMB Server | 4016871 +10 |
The same five steps every month, in the order that reduces risk fastest.
CVE-2017-0222 is rated Critical and scores 7.1 - a CVSS-sorted list would bury the one flaw attackers are already using. Sort by exploited, then publicly disclosed, then severity.
Patch Management vs Vulnerability Management: What's the Difference? →This release means 57 distinct update packages to deploy. Pilot on ring 0 within 24 hours and widen to production by day seven - never push the whole set everywhere at once.
What is Ring-Based Patch Deployment? A Guide to Progressive Rollouts →The Patch Management Lifecycle: 6 Stages from Discovery to Verification →Check the Windows release health dashboard before promoting past ring 1, and have the rollback path written down before you need it. Kernel, networking and authentication fixes are the ones that historically break things.
12 Patch Management Best Practices for 2026 →9 Chromium fixes for Edge shipped alongside this release on their own updater, and Adobe, SAP and Oracle release in the same week. OS-only patching leaves most of your real attack surface untouched.
What is Third-Party Patch Management and Why OS Patching Isn't Enough →Confirm the patch is actually present on each endpoint rather than trusting that "deployment succeeded". Keep the resulting report - it is the artefact auditors ask for, and reconstructing it later is far more work than capturing it now.
Patch Management: The Complete Guide →Trinetri does steps two through five automatically - detecting the 57 KB articles across every endpoint, staging them in rings, verifying installed state and producing the compliance evidence. See patch management →
Every month Microsoft has published back to January 2016, each with the same breakdown and the full CVE list.
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Patch Tuesday falls on the second Tuesday of every month, with updates going live at 10:00 a.m. Pacific Time. Microsoft introduced the practice in October 2003, following the Blaster worm, to cut distribution costs and give administrators a predictable cadence instead of patches arriving at random. The 10:00 a.m. timing is deliberate: it leaves a full working week to remediate before the weekend. Internally Microsoft calls it the "B" release; optional "C" and "D" preview releases follow later in the month. The next Patch Tuesday is November 10, 2026.
Microsoft fixed 57 vulnerabilities in May 2017, across Windows, Browser, System Center and Microsoft Office. 14 are rated Critical, 2 were publicly disclosed before the patch shipped, and 4 were already being exploited. Note that Microsoft's release document lists 77 entries in total, but 11 of those are Azure Linux package updates and 9 are republished Chromium fixes for Edge, which is why other sources sometimes quote a much larger number.
Exploit Wednesday is the day after Patch Tuesday. Attackers compare the newly released patches against the previous version to locate the flaw each one fixes, then build working exploits from that difference - often within 24 to 48 hours. It is the reason the deployment window matters as much as the patch itself: every hour a Critical remote code execution fix sits undeployed is an hour of measurable exposure.
A workable target for most organisations: actively exploited vulnerabilities within 24 hours, publicly disclosed ones within 72 hours, remaining Critical fixes within seven days, and everything else within the month. CISA's Known Exploited Vulnerabilities catalogue sets binding deadlines for US federal agencies and is a reasonable benchmark for everyone else. Stage the rollout in rings rather than deploying everywhere at once, so a regression is caught on a pilot group instead of in production.
An out-of-band update is a patch released outside the monthly cycle because the risk will not wait for the next Patch Tuesday. Microsoft issues them for actively exploited flaws with no mitigation - most famously during the WannaCry outbreak in 2017, when it took the unusual step of patching versions of Windows that were already out of support.
Yes. Adobe aligned its releases with Patch Tuesday in November 2012, and both SAP's Security Patch Day and Oracle's quarterly Critical Patch Updates are coordinated to the same week. Part of the reason is defensive: staggered releases let attackers reverse-engineer one vendor's patch to find the same underlying flaw in another's still-unpatched product. For IT teams it means the second Tuesday is rarely just a Microsoft problem.
Edge is built on Chromium, so most of its security fixes originate with the Chromium project and are republished by Microsoft under their own CVE identifiers. They ship on Chromium's cadence rather than the Patch Tuesday cycle, and they are delivered by Edge's own updater rather than Windows Update. Counting the 9 Edge entries alongside Microsoft product fixes would inflate the headline number and imply work for your Windows Update rings that does not exist.
