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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Deliver crafted Word document to victim
  2. Delivery
    Victim opens file in Word
  3. Exploit
    Trigger use-after-free in parser
  4. Execution
    Reclaim freed object with controlled data
  5. Persist
    Hijack execution flow
  6. Impact
    Run arbitrary code as user

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Memory lifecycle management
MITRE ATT&CK

2 techniques across 2 tactics: Execution, Privilege Escalation

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Exploitation requires a victim to open or preview an attacker-crafted Word document in an affected Office/Word build - the CVSS UI:R flag confirms user interaction is mandatory, which is the primary limiting factor. No authentication or prior privileges are needed (PR:N), and attack complexity is low (AC:L), so any successfully opened malicious file can trigger the flaw against default configurations; there is no special product feature or non-default setting required beyond running an unpatched affected version. The attack vector is local (AV:L), meaning the file must reach and be opened on the target host (e.g., via email, download, or share) rather than being exploited remotely without interaction. For SharePoint SKUs, exposure additionally depends on server-side Office document-processing being in use.

Impact

The CVSS 3.1 vector (AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H, 7.8 High) describes a low-complexity flaw needing no privileges but requiring the victim to open a file - the classic 'send a document, user opens it' Office pattern, which is local vector but network-deliverable via email or download. High confidentiality, integrity, and availability impact reflect full code execution in the user's context. No EPSS score, SSVC decision, or KEV entry was provided, and no POC is referenced, so current signals point to a real but not-yet-actively-exploited risk. The broad affected footprint and the low exploitation complexity make this a meaningful patch priority for any environment running Office; however, the reliance on user interaction and the absence of known exploitation or public POC place it below actively-exploited zero-days in urgency. Note the tag list includes 'Denial Of Service' whereas the description and CVSS emphasize code execution - the code-execution characterization from Microsoft's own vector should be treated as primary.

Exploit ScenarioDerived

An attacker emails a booby-trapped Word document (or hosts it for download) to a target and uses social engineering to get the victim to open it; when Word parses the file, the use-after-free is triggered and attacker-controlled heap data hijacks execution, running code in the victim's user context. No authentication or elevated privileges are needed, but the AV:L/UI:R vector means the victim must open the file. No public exploit is identified at time of analysis.

Act Now Prioritize within 24-48h. Why: Active threat signals + CRITICAL/HIGH severity.
Patch available 0.3% exploitation probability (EPSS)

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AnalysisAIv1 – Jul 14, 2026

Local code execution in Microsoft Office Word (across Microsoft 365 Apps, Office 2019/LTSC 2021/2024, Office for Mac, and Word 2016) allows an attacker to run arbitrary code by exploiting a use-after-free memory corruption flaw when a victim opens a maliciously crafted document. The CVSS 3.1 base score is 7.8 with a local attack vector requiring user interaction; there is no public exploit identified at time of analysis and the flaw is not listed in CISA KEV. Microsoft, which reported the issue itself, has released a patch.

RemediationAI

Patch available per vendor advisory - apply Microsoft's updates for every affected Office and SharePoint SKU as listed in the MSRC guidance at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55032 (exact fixed build numbers were not included in the source data and should be taken from that advisory per product and update channel). For managed Office deployments, ensure the relevant Current/Monthly/Semi-Annual or LTSC channel receives the update and confirm Mac Office builds are updated separately. Until patching completes, reduce exposure by opening untrusted Word documents in Protected View / Application Guard (which sandboxes rendering, at the cost of disabling editing and some features), enforcing Office macro and Mark-of-the-Web restrictions, and filtering inbound Office attachments at the mail gateway; on SharePoint, restrict or disable server-side Office/Word document rendering services where feasible, accepting the trade-off of lost in-browser document preview/editing functionality.

Affected VersionsENISA

Microsoft 365 Apps for Enterprise 16.0.1 <https://aka.ms/OfficeSecurityReleases
Microsoft Office LTSC 2021 16.0.1 <https://aka.ms/OfficeSecurityReleases
Microsoft Office 2019 19.0.0 <https://aka.ms/OfficeSecurityReleases
Microsoft SharePoint Server 2019 16.0.0 <16.0.10417.20175
Microsoft SharePoint Enterprise Server 2016 16.0.0 <16.0.5561.1001
Microsoft Office LTSC for Mac 2024 16.0.0 <16.111.26071215
Microsoft SharePoint Server Subscription Edition 16.0.0 <16.0.19725.20434
Microsoft Office LTSC 2024 16.0.0 <https://aka.ms/OfficeSecurityReleases
Microsoft Word 2016 16.0.1 <16.0.5561.1000
Microsoft Office 365 for Mac 1.0.0 <16.111.26071215
Microsoft Office LTSC for Mac 2021 16.0.1 <16.111.26071215

Affected Packages

microsoft 365_apps_for_enterprise_https_aka_ms_officesecurityreleases fix: Microsoft 365 Apps for Enterprise for 32-bit Systems https://aka.ms/OfficeSecurityReleases, Microsoft 365 Apps for Enterprise for 64-bit Systems https://aka.ms/OfficeSecurityReleases
microsoft office_2019_editions_https_aka_ms_officesecurityreleases fix: Microsoft Office 2019 for 32-bit editions https://aka.ms/OfficeSecurityReleases, Microsoft Office 2019 for 64-bit editions https://aka.ms/OfficeSecurityReleases
microsoft office_365_for_mac_16_111_26071215 fix: Microsoft Office 365 for Mac 16.111.26071215
microsoft office_ltsc_2021_editions_https_aka_ms_officesecurityreleases fix: Microsoft Office LTSC 2021 for 32-bit editions https://aka.ms/OfficeSecurityReleases, Microsoft Office LTSC 2021 for 64-bit editions https://aka.ms/OfficeSecurityReleases
microsoft office_ltsc_2024_editions_https_aka_ms_officesecurityreleases fix: Microsoft Office LTSC 2024 for 32-bit editions https://aka.ms/OfficeSecurityReleases, Microsoft Office LTSC 2024 for 64-bit editions https://aka.ms/OfficeSecurityReleases
microsoft office_ltsc_for_mac_2021_16_111_26071215 fix: Microsoft Office LTSC for Mac 2021 16.111.26071215
microsoft office_ltsc_for_mac_2024_16_111_26071215 fix: Microsoft Office LTSC for Mac 2024 16.111.26071215
microsoft sharepoint_enterprise_server_2016_16_0_5561_1001 fix: Microsoft SharePoint Enterprise Server 2016 16.0.5561.1001
microsoft sharepoint_server_2019_16_0_10417_20175 fix: Microsoft SharePoint Server 2019 16.0.10417.20175
microsoft sharepoint_server_subscription_edition_16_0_19725_20434 fix: Microsoft SharePoint Server Subscription Edition 16.0.19725.20434
microsoft word_2016_32_bit_edition_16_0_5561_1000 fix: Microsoft Word 2016 (32-bit edition) 16.0.5561.1000
microsoft word_2016_64_bit_edition_16_0_5561_1000 fix: Microsoft Word 2016 (64-bit edition) 16.0.5561.1000
euvd microsoft_office_365_for_mac fix: 16.111.26071215
euvd microsoft_office_ltsc_for_mac_2021 fix: 16.111.26071215
euvd microsoft_office_ltsc_for_mac_2024 fix: 16.111.26071215
euvd microsoft_sharepoint_enterprise_server_2016 fix: 16.0.5561.1001
euvd microsoft_sharepoint_server_2019 fix: 16.0.10417.20175
euvd microsoft_sharepoint_server_subscription_edition fix: 16.0.19725.20434
euvd microsoft_word_2016 fix: 16.0.5561.1000

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 19 packages in microsoft, euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

The root cause is CWE-416 (Use After Free): the Word document-parsing/rendering code frees a memory object but retains and later dereferences a dangling pointer to it, allowing an attacker who controls the reused heap memory to redirect execution. Use-after-free defects in Office file parsers are a classic and reliably exploitable memory-corruption class because attacker-controlled document structures can groom the heap to place controlled data where the freed object was. The CPE set shows the shared Office code affects the entire Office family - Microsoft 365 Apps for Enterprise, Office 2019, Office LTSC 2021 and 2024, Office 365/LTSC for Mac 2021 and 2024, Word 2016 - and, because SharePoint servers embed Office document-handling components (Office Web Apps/Word services), SharePoint Enterprise Server 2016, SharePoint Server 2019, and SharePoint Server Subscription Edition are also enumerated as affected.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Sources disagree (Medium–Critical)
Vendor (microsoft) PRIMARY 7.8 HIGH
AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
ENISA EUVD CRITICAL
CIRCL (temporal) 6.8 MEDIUM
vuln.today AI 7.8 HIGH

File must be opened locally so AV:L with UI:R; no privileges needed (PR:N) and low complexity (AC:L); code execution yields full C:H/I:H/A:H.

3.1 AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
4.0 AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

vuln.today treats the vendor’s rating as authoritative. A higher third-party CVSS (e.g. CISA-ADP) is shown for transparency but does not drive the headline severity.

CVSS VectorVendor: microsoft

Attack Vector
Local
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

DescriptionCVE.org

Use after free in Microsoft Office Word allows an unauthorized attacker to execute code locally.

Executive ViewAI

Why It Matters

A use-after-free vulnerability in Microsoft Office Word enables arbitrary code execution when users open maliciously crafted documents, affecting Office 365 Apps, Office 2019, Office LTSC 2021/2024, Office for Mac, and Word 2016. With nearly universal Office adoption across enterprise environments, this vulnerability poses significant risk for social-engineering-based attacks that bypass traditional security controls. A vendor patch is available for immediate deployment.

Business Impact: High
Compensating Controls

Apply vendor patch.

Threat Intelligence Overview

EPSS Score
0.3%
Top 77% exploitable
Prevalence
Ubiquitous
Microsoft Word/Office is deployed across the vast majority of enterprise environments
EU Gov Alert
Listed
Top-tier national CERT alert
Threat Intel
1
1 sources
Vendor Action
See Below
Required. The vulnerability documented by this CVE requires customer action to resolve.
Vendor Status
Publicly Disclosed:No
Exploited:No
Latest Software Release:Exploitation Less Likely
Data Quality
6 sources
Confidence: High

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC No
EPSS 0.3%
Patch available Yes
Active threat Yes
Deciding rule
Active threat signals + CRITICAL/HIGH severity
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision
Scheduled
Exploitation
None
System Exposure· derived
Small
Automatable
No
Human Impact
High
Technical Impact
Total

Priority Score

59
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +39
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: +20

Attack Technique

Use-after-free vulnerabilities occur when a program continues to access memory through a pointer after that memory has been deallocated.

Memory corruption occurs when a program writes data beyond the boundaries of allocated memory regions or accesses memory in unintended ways, violating the integrity of the process's address space.

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.

CVE-2026-50522 CRITICAL POC
9.8 Jul 14

Remote code execution in Microsoft SharePoint Server (2016, 2019, and Subscription Edition) lets an unauthenticated atta

CVE-2026-58644 CRITICAL POC
9.8 Jul 14

Remote code execution in Microsoft SharePoint (Enterprise Server 2016, Server 2019, and Server Subscription Edition) all

CVE-2026-55040 CRITICAL POC
9.1 Jul 14

Security feature bypass in Microsoft SharePoint (Enterprise Server 2016, Server 2019, and Server Subscription Edition) l

CVE-2026-56164 CRITICAL POC
9.8 Jul 14

Privilege elevation in Microsoft SharePoint Server (Enterprise Server 2016, Server 2019, and Subscription Edition) lets

CVE-2026-45659 HIGH POC
8.8 May 22

Authenticated remote code execution in Microsoft SharePoint (Enterprise Server 2016, Server 2019, and Subscription Editi

CVE-2026-58277 HIGH
8.8 Jul 14

Privilege elevation in Microsoft SharePoint Server (Enterprise Server 2016 and Server 2019) allows an authenticated netw

CVE-2026-55052 HIGH
8.8 Jul 14

Privilege escalation in Microsoft SharePoint Server (Enterprise Server 2016, Server 2019, and Subscription Edition) lets

CVE-2026-55034 HIGH
8.7 Jul 14

Cross-site scripting (CWE-79) in on-premises Microsoft SharePoint Server allows an authenticated, low-privileged attacke

CVE-2026-55021 HIGH
8.7 Jul 14

Spoofing via stored cross-site scripting in Microsoft SharePoint (Enterprise Server 2016, Server 2019, and Subscription

CVE-2026-55033 HIGH
7.8 Jul 14

Local code execution in Microsoft Word (and Office/SharePoint components that render Word content) stems from an integer

CVE-2026-55038 HIGH
7.8 Jul 14

Arbitrary code execution in Microsoft Office Word (and the broader Office/365/SharePoint family) arises from a stack-bas

CVE-2026-55132 HIGH
7.8 Jul 14

Local code execution in Microsoft Word (part of Microsoft 365 Apps, Office 2019, Office LTSC 2021/2024, and Office for M

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