EUVD-2026-44155
GHSA-r8f5-8f3p-vxp4
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessDeliver crafted Office document via phishing
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DeliveryUser opens file and exits Protected View
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ExploitMalformed structure overflows heap buffer during parsing
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ExecutionCorrupt heap metadata to hijack control flow
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ImpactExecute arbitrary code as current user
Vulnerability Assessment
| Weakness |
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Heap buffer bounds checking
MITRE ATT&CK
1 technique across 1 tactic: Execution 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 an attacker-supplied malicious Office document in an affected build of Microsoft Office (365 Apps for Enterprise, Office 2016/2019, or Office LTSC 2021/2024) - the CVSS UI:R confirms user interaction is mandatory, which is the primary limiting factor. No attacker authentication is needed (PR:N) and complexity is low (AC:L), but the 'local' vector (AV:L) reflects that code runs only after a user opens the crafted file locally rather than through remote network reach. Microsoft's Protected View / Mark-of-the-Web sandboxing further limits exploitation for documents received from email or the internet unless the user chooses to enable editing, and execution is bound to the opening user's privileges (S:U), not automatic escalation. |
| Impact | The CVSS 3.1 base score is 7.8 (High) with vector AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H - the 'local' attack vector here reflects that the victim must open a file (UI:R), not that the attacker needs prior local access, which is typical for document-parsing bugs. PR:N means no attacker authentication is required, but the required user interaction meaningfully lowers real-world exploitability. CISA's SSVC decision framework corroborates a measured priority: Exploitation is 'none' (no observed or public exploitation), Automatable is 'no' (user interaction prevents mass, hands-off exploitation), while Technical Impact is 'total' - consistent with the full C/I/A compromise in the CVSS vector. No EPSS score was provided, and there is no KEV listing or POC in the input, so this reads as a genuinely severe-if-exploited but not currently-weaponized issue: patch on a normal-to-prompt cadence rather than emergency, prioritizing high-exposure users who handle untrusted documents. |
| Exploit ScenarioDerived | An attacker crafts a malicious Office document with a corrupted structure that overflows a heap buffer during parsing, then delivers it via phishing email or a web download. When the targeted user opens the file (and, if prompted, exits Protected View), the overflow executes attacker-controlled code with that user's privileges. No public exploit is identified at time of analysis, and the low attack complexity (AC:L) means a working exploit would be reliable once developed, but the required user interaction limits scale. |
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Alert meAnalysisAIv1 – Jul 14, 2026
Local code execution in Microsoft Office (Microsoft 365 Apps for Enterprise, Office 2016/2019, and Office LTSC 2021/2024) arises from a heap-based buffer overflow (CWE-122) that an attacker triggers by convincing a user to open a maliciously crafted Office document. Successful exploitation yields full code execution in the context of the current user, with high impact to confidentiality, integrity, and availability. There is no public exploit identified at time of analysis and it is not listed in CISA KEV; SSVC rates current exploitation as none.
RemediationAI
Patch available per vendor advisory: apply the Microsoft security update for CVE-2026-50301 from the MSRC update guide at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50301, which lists the fixed build for each affected channel (Microsoft 365 Apps for Enterprise, Office 2016, Office 2019, Office LTSC 2021, and Office LTSC 2024); the input does not specify an exact fixed version, so pull the precise build from that advisory. For Microsoft 365 Apps, ensure the click-to-run update channel is current; for Office 2016/2019/LTSC, deploy the corresponding cumulative/security update via WSUS, Microsoft Update, or Intune. As interim compensating controls until patching completes, enforce Protected View and 'Block macros/active content from the Internet' so files from email and web open in a sandboxed read-only state, use Mark-of-the-Web-aware handling to keep downloaded documents in Protected View, and restrict or block inbound Office attachments from untrusted senders at the mail gateway - the trade-off is that aggressive Protected View or attachment blocking can disrupt legitimate document workflows and requires user awareness to avoid users clicking 'Enable Editing' on hostile files.
Affected VersionsENISA
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 1 package in euvd
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
The flaw is a CWE-122 heap-based buffer overflow within Microsoft Office's document parsing/rendering code. Heap overflows occur when a function writes more data into a heap-allocated buffer than it was sized for, corrupting adjacent heap metadata or object pointers; in file-format parsers this typically stems from trusting an attacker-controlled length or count field in the document structure. The affected CPEs identify the Office application family (microsoft_365_apps_for_enterprise, microsoft_office_2016, microsoft_office_2019, microsoft_office_ltsc_2021, microsoft_office_ltsc_2024), meaning the vulnerable component is shared Office code rather than a single standalone application. Because Office documents are a routine email and web delivery vector, a parser-level memory-corruption bug of this class is a classic path to client-side code execution.
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Severity by source
AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Client-side document parsing bug: attacker needs no auth (PR:N) but victim must open the file (UI:R, AV:L), and successful memory corruption yields full C/I/A compromise as the user.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
DescriptionCVE.org
Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code locally.
Executive ViewAI
Microsoft Office users face a critical vulnerability enabling full system compromise through specially crafted documents. While no public exploit has been identified, the direct breach path and ubiquity of Office in enterprise environments make this a material threat to data confidentiality, integrity, and business operations.
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Threat Intelligence Overview
NVD
CVE.org
EPSS
Vulnrichment
VulDB
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.
What every action level means
SSVC AssessmentENISA
Priority Score
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.
A heap overflow occurs when a program writes data beyond the bounds of a buffer allocated in the heap memory region.
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Exploit-DB