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Microsoft Patch Tuesday
December 2018

Microsoft's December 2018 Patch Tuesday fixes 41 vulnerabilities across Windows, Browser and Microsoft Office - 11 rated Critical, 1 publicly disclosed before the patch shipped, 2 already exploited in the wild. Patch CVE-2018-8653 first.

Released December 11, 2018, 10:00 PT2 actively exploited1 publicly disclosed76 KB articles to deploy

December 2018 Patch Tuesday at a glance

41
Microsoft CVEs
excl. Edge & Azure Linux
11
Critical
27% of the release
2
Actively exploited
CVE-2018-8653
1
Publicly disclosed
known before the patch
9.8
Highest CVSS
CVE-2018-8626
76
KB articles
what you actually deploy

Why this number differs from other roundups. Microsoft's December 2018 release document lists 53 entries. 12 are Azure Linux (Mariner) OS package updates and 0 are republished Chromium fixes for Edge - neither is a Microsoft product vulnerability. The 41 above is the real Patch Tuesday set. See the breakdown →

Priority order

Patch these first

Ranked by exploitation reality, not score alone. This month's exploited flaw is rated Critical - a severity-sorted list would bury it.

The numbers

What’s in this release

Where the 53 entries actually come from

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

41 Microsoft products12 Azure Linux (Mariner)

Severity

Microsoft channel only · 41 CVEs

December 2018 severity breakdown
Critical11
Important30
Moderate0
Low0

Impact type

What an attacker gains if it works

December 2018 impact breakdown
Remote Code Execution19
Information Disclosure11
Elevation of Privilege5
Denial of Service3
Spoofing2
Tampering1

Most-affected components

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

Microsoft Scripting Engine7Microsoft Office6Windows Kernel6Microsoft Graphics Component4Internet Explorer3Microsoft Office SharePoint3.NET Framework2Microsoft Windows DNS2Adobe Flash Player1Microsoft Dynamics1Microsoft Exchange Server1Microsoft Windows1
Every patch

Browse all 53 entries

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

Showing 41 of 41
41 Microsoft vulnerabilities in the December 2018 Patch Tuesday, sortable by severity, CVSS and exploit status.
TitleStatusKB
CriticalCVE-2018-8653Scripting Engine Memory Corruption VulnerabilityRCE7.5ExploitedInternet Explorer4483187 +6
ImportantCVE-2018-8611Windows Kernel Elevation of Privilege VulnerabilityEoP7.0ExploitedWindows Kernel4471318 +13
ImportantCVE-2018-8517.NET Framework Denial Of Service VulnerabilityDoS-Disclosed.NET Framework4470491 +24
CriticalCVE-2018-8631Internet Explorer Memory Corruption VulnerabilityRCE7.5More likelyInternet Explorer4470199 +10
CriticalCVE-2018-8583Chakra Scripting Engine Memory Corruption VulnerabilityRCE4.2More likelyMicrosoft Scripting Engine4471324 +3
CriticalCVE-2018-8617Chakra Scripting Engine Memory Corruption VulnerabilityRCE4.2More likelyMicrosoft Scripting Engine4471321 +5
CriticalCVE-2018-8618Chakra Scripting Engine Memory Corruption VulnerabilityRCE4.2More likelyMicrosoft Scripting Engine4471321 +4
CriticalCVE-2018-8624Chakra Scripting Engine Memory Corruption VulnerabilityRCE4.2More likelyMicrosoft Scripting Engine4471321 +4
CriticalCVE-2018-8629Chakra Scripting Engine Memory Corruption VulnerabilityRCE4.2More likelyMicrosoft Scripting Engine4471321 +5
CriticalCVE-2018-8634Microsoft Text-To-Speech Remote Code Execution VulnerabilityRCE4.2More likelyWindows Authentication Methods4471321 +5
ImportantCVE-2018-8619Internet Explorer Remote Code Execution VulnerabilityRCE7.5More likelyInternet Explorer4470199 +10
ImportantCVE-2018-8625Windows VBScript Engine Remote Code Execution VulnerabilityRCE7.5More likelyMicrosoft Scripting Engine4470199 +10
ImportantCVE-2018-8643Scripting Engine Memory Corruption VulnerabilityRCE7.5More likelyMicrosoft Scripting Engine4470199 +10
ImportantCVE-2018-8599Diagnostics Hub Standard Collector Service Elevation of Privilege VulnerabilityEoP7.0More likelyVisual Studio4469516 +6
ImportantCVE-2018-8639Win32k Elevation of Privilege VulnerabilityEoP7.0More likelyMicrosoft Graphics Component4471318 +13
ImportantCVE-2018-8641Win32k Elevation of Privilege VulnerabilityEoP7.0More likelyWindows Kernel-Mode Drivers4471318 +13
ImportantCVE-2018-8595Windows GDI Information Disclosure VulnerabilityInfo Disc.4.7More likelyMicrosoft Graphics Component4471318 +13
ImportantCVE-2018-8596Windows GDI Information Disclosure VulnerabilityInfo Disc.4.7More likelyMicrosoft Graphics Component4471318 +13
ImportantCVE-2018-8612Connected User Experiences and Telemetry Service Denial of Service VulnerabilityDoS4.7More likelyWindows Kernel4471321 +4
ImportantCVE-2018-8637Win32k Information Disclosure VulnerabilityInfo Disc.4.7More likelyWindows Kernel4471324 +1
ImportantCVE-2018-8638DirectX Information Disclosure VulnerabilityInfo Disc.4.7More likelyMicrosoft Graphics Component4471332
ImportantCVE-2018-8477Windows Kernel Information Disclosure VulnerabilityInfo Disc.3.3More likelyWindows Kernel4471318 +13
ImportantCVE-2018-8587Microsoft Outlook Remote Code Execution VulnerabilityRCE-More likelyMicrosoft Office4461544 +2
ImportantCVE-2018-8597Microsoft Excel Remote Code Execution VulnerabilityRCE-More likelyMicrosoft Office4461542 +4
ImportantCVE-2018-8628Microsoft PowerPoint Remote Code Execution VulnerabilityRCE-More likelyMicrosoft Office2597975 +10
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 76 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 41 vulnerabilities in December 2018, across Windows, Browser, Microsoft Office and Developer Tools. 11 are rated Critical, 1 were publicly disclosed before the patch shipped, and 2 were already being exploited. Note that Microsoft's release document lists 53 entries in total, but 12 of those are Azure Linux package updates and 0 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 0 Edge entries alongside Microsoft product fixes would inflate the headline number and imply work for your Windows Update rings that does not exist.