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Microsoft Patch Tuesday
August 2017

Microsoft's August 2017 Patch Tuesday fixes 45 vulnerabilities across Browser, Windows and Developer Tools - 27 rated Critical, 2 publicly disclosed before the patch shipped. No active exploitation this month, so lead with the 26 Critical remote code execution fixes.

Released August 8, 2017, 10:00 PT2 publicly disclosed46 KB articles to deploy

August 2017 Patch Tuesday at a glance

45
Microsoft CVEs
excl. Edge & Azure Linux
27
Critical
60% of the release
0
Actively exploited
none this month
2
Publicly disclosed
known before the patch
8.8
Highest CVSS
CVE-2017-8624
46
KB articles
what you actually deploy

Why this number differs from other roundups. Microsoft's August 2017 release document lists 55 entries. 3 are Azure Linux (Mariner) OS package updates and 7 are republished Chromium fixes for Edge - neither is a Microsoft product vulnerability. The 45 above is the real Patch Tuesday set. See the breakdown →

Priority order

Patch these first

Ranked by exploitation reality, not score alone. Nothing is under active attack this month, so the Critical remote-code-execution fixes lead.

Patch today

Exploited in the wild

Confirmed attacks are already happening. Emergency change window.

No actively exploited vulnerabilities in this release.

The numbers

What’s in this release

Where the 55 entries actually come from

Most roundups quote a single number. These are three unrelated release streams.

45 Microsoft products3 Azure Linux (Mariner)7 Edge (Chromium)

Severity

Microsoft channel only · 45 CVEs

August 2017 severity breakdown
Critical27
Important17
Moderate1
Low0

Impact type

What an attacker gains if it works

August 2017 impact breakdown
Remote Code Execution29
Elevation of Privilege5
Information Disclosure4
Denial of Service4
Security Feature Bypass2
Spoofing1

Most-affected components

Where this month’s fixes concentrate - filter by any of them in the table below

Microsoft Scripting Engine21Internet Explorer4Windows Kernel-Mode Drivers3Microsoft Windows2Windows Hyper-V2Windows Subsystem for Linux2Adobe Flash Player1Common Log File System Driver1Microsoft JET Database Engine1Microsoft Office1Microsoft Windows PDF1Microsoft Windows Search Component1
Every patch

Browse all 55 entries

Sorted by risk by default: exploited first, then publicly disclosed, then severity, then CVSS. Search by CVE, title, component or KB number.

Showing 45 of 45
45 Microsoft vulnerabilities in the August 2017 Patch Tuesday, sortable by severity, CVSS and exploit status.
TitleStatusKB
ImportantCVE-2017-8633Windows Error Reporting Elevation of Privilege VulnerabilityEoP7.5DisclosedMore likelyMicrosoft Windows4034658 +10
ImportantCVE-2017-8627Windows Subsystem for Linux Denial of Service VulnerabilityDoS4.4DisclosedWindows Subsystem for Linux4034674
CriticalCVE-2017-8620Windows Search Remote Code Execution VulnerabilityRCE8.1More likelyMicrosoft Windows Search Component4034034 +10
CriticalCVE-2017-8635Scripting Engine Memory Corruption VulnerabilityRCE7.5More likelyMicrosoft Scripting Engine4034658 +7
CriticalCVE-2017-8636Scripting Engine Memory Corruption VulnerabilityRCE7.5More likelyMicrosoft Scripting Engine4034658 +7
CriticalCVE-2017-8669Microsoft Browser Memory Corruption VulnerabilityRCE7.5More likelyInternet Explorer4034658 +6
CriticalCVE-2017-8518Microsoft Edge Memory Corruption VulnerabilityRCE4.2More likelyMicrosoft Scripting Engine4022714 +3
CriticalCVE-2017-8634Scripting Engine Memory Corruption VulnerabilityRCE4.2More likelyMicrosoft Scripting Engine4034674
CriticalCVE-2017-8639Scripting Engine Memory Corruption VulnerabilityRCE4.2More likelyMicrosoft Scripting Engine4034658 +1
CriticalCVE-2017-8640Scripting Engine Memory Corruption VulnerabilityRCE4.2More likelyMicrosoft Scripting Engine4034658 +3
CriticalCVE-2017-8641Scripting Engine Memory Corruption VulnerabilityRCE4.2More likelyMicrosoft Scripting Engine4034658 +7
CriticalCVE-2017-8645Scripting Engine Memory Corruption VulnerabilityRCE4.2More likelyMicrosoft Scripting Engine4034658 +2
CriticalCVE-2017-8653Microsoft Browser Memory Corruption VulnerabilityRCE4.2More likelyInternet Explorer4034658 +7
CriticalCVE-2017-8656Scripting Engine Memory Corruption VulnerabilityRCE4.2More likelyMicrosoft Scripting Engine4034658 +1
CriticalCVE-2017-8657Scripting Engine Memory Corruption VulnerabilityRCE4.2More likelyMicrosoft Scripting Engine4034658 +2
CriticalCVE-2017-8658Scripting Engine Memory Corruption VulnerabilityRCE4.2More likelyMicrosoft Scripting Engine—
CriticalCVE-2017-8670Scripting Engine Memory Corruption VulnerabilityRCE4.2More likelyMicrosoft Scripting Engine4034658 +1
CriticalCVE-2017-8671Scripting Engine Memory Corruption VulnerabilityRCE4.2More likelyMicrosoft Scripting Engine4034658 +2
CriticalCVE-2017-8674Scripting Engine Memory Corruption VulnerabilityRCE4.2More likelyMicrosoft Scripting Engine4034674
ImportantCVE-2017-8624Windows Common Log File System Driver Elevation of Privilege VulnerabilityEoP8.8More likelyCommon Log File System Driver4034658 +10
ImportantCVE-2017-8593Win32k Elevation of Privilege VulnerabilityEoP7.0More likelyWindows Kernel-Mode Drivers4034658 +10
ImportantCVE-2017-8666Win32k Information Disclosure VulnerabilityInfo Disc.7.0More likelyWindows Kernel-Mode Drivers4034658 +10
ImportantCVE-2017-8659Scripting Engine Information Disclosure VulnerabilityInfo Disc.4.3More likelyMicrosoft Scripting Engine4034674
CriticalCVE-2017-8591Windows IME Remote Code Execution VulnerabilityRCE8.8—Windows Shell4034658 +7
CriticalCVE-2017-8638Scripting Engine Memory Corruption VulnerabilityRCE4.2—Microsoft Scripting Engine4034674
Your move

What your IT team should do

The same five steps every month, in the order that reduces risk fastest.

Test the known-issue candidates

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 →

Verify installed state, then evidence it

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 46 KB articles across every endpoint, staging them in rings, verifying installed state and producing the compliance evidence. See patch management →

Archive

Previous Patch Tuesdays

Every month Microsoft has published back to January 2016, each with the same breakdown and the full CVE list.

Older months104 releases, October 2024 – January 2016
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Patch Tuesday FAQ

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 45 vulnerabilities in August 2017, across Browser, Windows, Developer Tools and Microsoft Office. 27 are rated Critical, 2 were publicly disclosed before the patch shipped, and 0 were already being exploited. Note that Microsoft's release document lists 55 entries in total, but 3 of those are Azure Linux package updates and 7 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 7 Edge entries alongside Microsoft product fixes would inflate the headline number and imply work for your Windows Update rings that does not exist.