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Microsoft Word CVE-2026-70206

| EUVDEUVD-2026-99707 MEDIUM
Out-of-bounds Read (CWE-125)
2026-10-13 secure@microsoft.com GHSA-r77v-2p5v-j24q
6.5
CVSS 3.1 · Vendor: microsoft
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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 malicious file
  3. Exploit
    Trigger out-of-bounds read in parser
  4. Execution
    Leak adjacent process memory
  5. Impact
    Exfiltrate disclosed information to attacker

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Bounds checking, read limits
MITRE ATT&CK

1 technique across 1 tactic: Collection

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

Exploitation Conditions

Exploitation requires the victim to open a maliciously crafted Word document (CVSS UI:R) - there is no server-side or zero-click path here; delivery is typically via email attachment, download, or shared file. No authentication or prior privileges on the target are needed (PR:N), and the attack vector is network/remote in that the document is delivered remotely, but the actual trigger is local document parsing in Word. The primary limiting factor is mandatory user interaction: without a user opening the file, the flaw cannot be triggered, which is also why CISA SSVC rates it Automatable=no. Affected products span Office LTSC 2021/2024, Microsoft 365 Apps for Enterprise, and Office LTSC/365 for Mac; a vendor patch is available and applying it eliminates the condition.

Impact

This is a moderate-severity information disclosure flaw with a consistent, coherent signal set that points to LOW real-world urgency despite affecting a ubiquitous product. The CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N, base 6.5) describes a network-reachable, low-complexity, unauthenticated bug whose exploitation hinges on user interaction (UI:R) - the victim must open a crafted Word document. Impact is confidentiality-only (C:H/I:N/A:N), fitting the CWE-125 out-of-bounds read: an attacker can leak memory contents but cannot alter data or crash the service through this vector. The CISA SSVC framework reinforces low priority: Exploitation=none (no observed or public exploitation), Automatable=no (mass/automated exploitation is impractical because each attack needs a human to open a document), and Technical Impact=partial. EPSS was not provided in the input, so probabilistic exploitation likelihood cannot be quantified here. This vulnerability is NOT in CISA KEV and no POC is referenced. The signals do not conflict - a widely deployed product (Office Word) with a genuine memory-disclosure bug, but gated behind user interaction and showing no exploitation activity. One caveat to verify: C:H is rated High, yet an out-of-bounds read typically leaks adjacent memory of uncertain value; whether this reliably discloses sensitive data (vs. limited/bounded leakage) should be confirmed against Microsoft's advisory. Overall this is a patch-in-normal-cycle issue, not an emergency.

Exploit ScenarioDerived

An attacker emails or otherwise delivers a specially crafted Word document to a target and uses social engineering to get them to open it. When Word parses the malformed structure, an out-of-bounds read occurs and process memory contents are disclosed back to the attacker over the network. No public exploit code is referenced, and successful exploitation depends entirely on the victim opening the file.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.9% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 14, 2026

Out-of-bounds read in Microsoft Office Word allows a remote, unauthenticated attacker to disclose the contents of memory beyond the bounds of an allocated buffer when a victim opens a specially crafted document (CVSS 6.5, AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N). Affected builds include Office LTSC 2021 and 2024 for Windows, Microsoft 365 Apps for Enterprise, and the Office LTSC/365 editions for Mac, so the exposure footprint is essentially the entire supported Microsoft Office desktop install base. Impact is confidentiality-only - read access to process memory, with no integrity or availability effect and no demonstrated code execution path - and the flaw cannot be triggered without the user opening the malicious file. No public exploit code or active exploitation has been identified at time of analysis, and CISA's SSVC assessment rates exploitation as none and automatable as no, keeping real-world urgency low despite the ubiquitous target.

RemediationAI

Vendor-released patch: Microsoft Office LTSC 2024 version 16.0.17932.21056 and Microsoft Office LTSC 2021 version 16.0.14334.20974, with the corresponding fixed builds for Microsoft 365 Apps for Enterprise and the Office LTSC 2021/2024 and Office 365 for Mac channels published through https://aka.ms/OfficeSecurityReleases; consult the vendor advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-70206 for the Mac build identifiers, then deploy through your normal update channel (Microsoft Update, Click-to-Run, or Configuration Manager/Intune) and verify the reported build number, since Office frequently has multiple channel builds in the field. Because the flaw only triggers on opening a crafted document, interim compensating controls are practical: enforce Protected View and Mark-of-the-Web so files from the internet or email attachments open in a sandboxed, read-only view rather than full trust - the trade-off is additional prompts and occasional rendering/editing limitations for legitimate macro-free documents; block risky legacy formats (.doc, .rtf) at the email gateway and file-share boundary, accepting that some business workflows depending on legacy templates will break; and disable or restrict ActiveX controls and OLE embedded objects via the Trust Center or Group Policy, which reduces parser attack surface at the cost of breaking documents that legitimately embed such objects. Given SSVC exploitation=none and no public exploit identified at time of analysis, patch deployment can follow a standard monthly cycle targeted first at users who routinely open externally sourced Word files, rather than an emergency out-of-band push.

Affected VersionsENISA

Microsoft Office LTSC for Mac 2021 16.0.1 <publication
Microsoft Office 365 for Mac 1.0.0 <publication
Microsoft Office LTSC 2024 16.0.0 <16.0.17932.21056
Microsoft Office LTSC for Mac 2024 16.0.0 <publication
Microsoft 365 Apps for Enterprise 16.0.1 <https://aka.ms/OfficeSecurityReleases
Microsoft Office LTSC 2021 16.0.1 <16.0.14334.20974

Affected Packages

euvd microsoft_office_ltsc_2021 fix: 16.0.14334.20974
euvd microsoft_office_ltsc_2024 fix: 16.0.17932.21056

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 2 packages in 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 an out-of-bounds read (CWE-125), a memory-safety class in which the parser reads past the end of an allocated buffer because a length, offset, or index value derived from the input file is not validated against the true buffer size. In Word this class typically surfaces in the OLE/Office binary format parsers, embedded object handlers, or graphics/table parsing code that consume the compound file structure of a .doc/.docx container. The CVSS vector AV:N/AC:L/PR:N/UI:R confirms the trigger is local document parsing inside the Word client but that the malicious file arrives over the network: no credentials or prior foothold are needed, but user interaction is mandatory because the file must be opened for the parser to run. The scoring reflects a partial technical impact - an information leak (C:H) without modification or denial of service - consistent with CISA SSVC's Technical Impact: partial and Automatable: no, since reliable exploitation generally requires attacker-crafted file content plus victim action rather than a spray-and-pray payload. The CPE/version data supplied by ENISA EUVD pins affected builds to Office LTSC 2024 below 16.0.17932.21056, Office LTSC 2021 below 16.0.14334.20974, Microsoft 365 Apps for Enterprise at 16.0.1 (updates tracked via the Office Security Releases page), and the Mac LTSC 2021/2024 and Office 365 for Mac branches where the fixed build is documented by Microsoft's publication rather than a discrete version boundary.

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Severity by source

Vendor (microsoft) PRIMARY 6.5 MEDIUM
AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
vuln.today AI 6.5 MEDIUM

Remote crafted document, no privileges (PR:N) but user must open it (UI:R); out-of-bounds read discloses memory (C:H) with no integrity or availability impact.

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

Primary rating from Vendor (microsoft).

CVSS VectorVendor: microsoft

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

Lifecycle Timeline

2
Patch available
Oct 13, 2026 - 20:20 EUVD
CVE Published
Oct 13, 2026 - 19:19 cve.org
MEDIUM 6.5

DescriptionCVE.org

Out-of-bounds read in Microsoft Office Word allows an unauthorized attacker to disclose information over a network.

Threat Intelligence Overview

EPSS Score
0.9%
Top 43% exploitable
Prevalence
Ubiquitous
Microsoft Office/Word deployed across most enterprise and consumer environments
Vendor Status
Publicly Disclosed:No
Exploited:No
Latest Software Release:Exploitation Less Likely
Data Quality
5 sources
Confidence: Medium

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 MEDIUM
CISA KEV No
Public POC No
EPSS 0.9%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
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· derived
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact· derived
Medium
Technical Impact
Partial

Priority Score

33
Low Medium High Critical
KEV: 0
EPSS: +1
CVSS: +32
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

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