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Microsoft Excel CVE-2026-97745

| EUVDEUVD-2026-100305 HIGH
Use After Free (CWE-416)
2026-10-13 secure@microsoft.com GHSA-qxwx-fm93-2xpp
8.8
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 Excel file via phishing
  2. Delivery
    User opens malicious spreadsheet
  3. Exploit
    Trigger use-after-free in Excel parser
  4. Execution
    Execute arbitrary code as user
  5. Impact
    Compromise host confidentiality and integrity

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 user to open or preview an attacker-crafted Excel document (UI:R) in an affected build of Microsoft Office Excel - specifically Office LTSC 2021 (<16.0.14334.20974), Office LTSC 2024 (<16.0.17932.21056), Microsoft 365 Apps for Enterprise, and the Mac Office LTSC 2021/2024 and Office 365 for Mac variants. No attacker authentication or pre-existing privileges on the target are needed (PR:N), and no special non-default product configuration is required; the primary limiting factor is the mandatory user interaction of opening the malicious file, meaning the attack hinges on successful social engineering/phishing delivery rather than direct remote triggering. Code executes in the context of the current user, so a low-privileged user account constrains the immediate blast radius absent a separate privilege-escalation chain.

Impact

This is a genuine high-priority vulnerability for environments running Microsoft Office/Excel. The provided CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H, base 8.8) indicates a network-delivered, low-complexity flaw requiring no attacker privileges but requiring user interaction, with total loss of confidentiality, integrity, and availability on the host - consistent with code execution via a use-after-free (CWE-416) when a victim opens a malicious document. The single limiting signal is UI:R: exploitation depends on social engineering (a user opening a crafted file), which somewhat reduces mass-exploitation potential compared to a zero-click flaw. No EPSS score, no CISA KEV listing, and no POC indicator were supplied, so there is no public exploit identified at time of analysis and no evidence of active exploitation; SSVC exploitation status is therefore effectively 'none/no known exploitation' from the available data. The 'Denial Of Service' tag conflicts with the description and CVSS impact, both of which describe remote code execution, not merely DoS - treat the DoS label as incomplete. Overall: credible RCE class, patch available, but real-world risk is gated by user interaction and absence of confirmed exploitation, placing it as 'patch promptly' rather than 'emergency zero-day.'

Exploit ScenarioDerived

An attacker emails or hosts a specially crafted Excel spreadsheet and lures a user into opening it (e.g., a phishing attachment). When Excel parses the file, it triggers a use-after-free condition that the attacker leverages to execute arbitrary code in the context of the current user. No public exploit code is identified at time of analysis, and exploitation requires the victim to open the file (UI:R).

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.8% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 13, 2026

Remote code execution in Microsoft Excel allows an unauthenticated attacker to run arbitrary code in the context of the current user when a victim opens or previews a specially crafted spreadsheet, making this a genuine high-priority vulnerability for environments running Microsoft Office/Excel. The CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H, 8.8) shows no credentials or pre-existing privileges are needed, but because user interaction is required (UI:R) and no non-default configuration is involved, exploitation depends on social engineering - typically a phishing attachment, a malicious link, or a web-hosted document - rather than direct remote triggering. No public exploit code and no confirmed active exploitation (CISA KEV) were identified at time of analysis, and a vendor patch is available per Microsoft's advisory.

RemediationAI

Vendor-released patch: update Microsoft Office LTSC 2021 to 16.0.14334.20974 or later and Office LTSC 2024 to 16.0.17932.21056 or later, and bring Microsoft 365 Apps for Enterprise current through the Office security release channel at https://aka.ms/OfficeSecurityReleases; full guidance and per-channel builds are in the MSRC advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-97745 (patch status per vendor: available). For the Mac Office LTSC 2021, Office LTSC 2024, and Office 365 for Mac editions, the patched versions were marked as pending publication in the EUVD data, so track the MSRC advisory and apply the Mac update as soon as it ships. Until endpoints are patched, the effective compensating controls target the delivery and UI:R prerequisite: enforce Mark-of-the-Web on files from the internet and email and block users from removing it (trade-off: friction on legitimate downloaded files, and bypass is trivial if users click Enable Editing), keep or force Protected View for files from untrusted locations (trade-off: Protected View is user-bypassable via Enable Editing, so pair it with attachment sandboxing/detonation and macro-and-executable blocking at the mail and web gateway), and consider Microsoft Defender Application Guard for Office on Windows Enterprise to open untrusted documents in a disposable container (trade-off: reduced document functionality and extra performance/licensing overhead). Because code executes with the current user's rights, enforce least privilege and remove local admin rights to contain a successful hit, and tune EDR/ASR policies to flag Excel spawning child processes such as cmd.exe, powershell.exe, or mshta.exe, which is a strong post-exploitation signal for this class of memory-corruption exploit.

Affected VersionsENISA

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

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 a use-after-free (CWE-416) in Microsoft Excel's handling of document content: a heap object is released during processing while a reference to it is retained, so subsequent use of the dangling pointer corrupts memory in a way an attacker can steer toward controlled code execution. Because the flaw lives in the document-parsing path of the Office client rather than in a network service, the network attack vector (AV:N) reflects file delivery over email, messaging, or the web, while the mandatory user interaction (UI:R) reflects the victim opening or previewing the file; complexity is low (AC:L) and no privileges are required (PR:N), with scope unchanged (S:U) and high confidentiality, integrity, and availability impact (C:H/I:H/A:H). Impact is bounded by the privileges of the logged-on user, so a compromised low-privileged account constrains the immediate blast radius absent a separate privilege-escalation chain. Associated intelligence tags (Use After Free, Memory Corruption, Denial Of Service, Microsoft) and EUVD record EUVD-2026-100305 corroborate a memory-safety defect in the Excel client build range; no CPE strings were supplied in the feed, so exact affected builds are derived from the EUVD version boundaries for Office LTSC 2021, Office LTSC 2024, Microsoft 365 Apps for Enterprise, and the Mac Office builds.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (microsoft) PRIMARY 8.8 HIGH
AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
vuln.today AI 8.8 HIGH

File is delivered over the network (AV:N) but must be opened by the victim (UI:R); no attacker privileges (PR:N), and a UAF yielding code execution gives full C/I/A impact in the user's context.

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

Lifecycle Timeline

2
Patch available
Oct 13, 2026 - 20:20 EUVD
CVE Published
Oct 13, 2026 - 19:22 cve.org
HIGH 8.8

DescriptionCVE.org

Use after free in Microsoft Office Excel allows an unauthorized attacker to execute code over a network.

Executive ViewAI

Why It Matters

Microsoft Excel contains a high-severity remote code execution vulnerability (CVE-2026-97745) that allows an unauthenticated attacker to execute arbitrary code in the context of the current user when a victim opens or previews a specially crafted spreadsheet. This poses a significant risk to organizations where Excel is widely used, as exploitation relies on social engineering and could lead to unauthorized access, data theft, or further compromise. No public exploit or active exploitation has been observed, and a vendor patch is available, making timely patching the primary mitigation.

Business Impact: High
Compensating Controls

Apply vendor patch.

Threat Intelligence Overview

EPSS Score
0.8%
Top 44% exploitable
Prevalence
High
Microsoft Office/Excel is near-universal across enterprise desktops
Threat Intel
1
1 sources
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 HIGH
CISA KEV No
Public POC No
EPSS 0.8%
Patch available Yes
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
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
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact
High
Technical Impact
Total

Priority Score

45
Low Medium High Critical
KEV: 0
EPSS: +1
CVSS: +44
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

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.

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