EUVD-2026-56716
GHSA-5wpr-7g82-cf49
Severity by source
AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
File-format parsing flaw requires victim to open a crafted file locally (AV:L, UI:R); no authentication or privilege required of attacker; scope unchanged as execution stays within user process.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
3DescriptionCVE.org
Heap-based buffer overflow in Microsoft Office Access allows an unauthorized attacker to execute code locally.
AnalysisAI
Heap-based buffer overflow (CWE-122) in Microsoft Office Access enables local code execution when a user opens a specially crafted database file, with full high-impact compromise of confidentiality, integrity, and availability (CVSS 7.8). Affected products span Microsoft Access 2016 through Microsoft 365 Apps for Enterprise and Office LTSC 2024. No public exploit or CISA KEV listing has been identified at time of analysis; a vendor patch is available via the Microsoft Security Response Center.
Technical ContextAI
CWE-122 (Heap-based Buffer Overflow) describes a condition where a program writes past the end of an allocated heap buffer, corrupting adjacent heap metadata or data. Microsoft Office Access uses the ACE/JET database engine to parse .accdb and .mdb file formats; the overflow likely occurs during processing of a malformed record, index, or schema structure within such a file. Affected CPE strings span Access 2016 (16.0.0 through <16.0.5565.1000 in both 32-bit and standard editions), Office 2019 (19.0.0), Office LTSC 2021, Office LTSC 2024, and Microsoft 365 Apps for Enterprise at version 16.0.1, all per ENISA EUVD-2026-56716. The local attack vector (AV:L) with required user interaction (UI:R) is consistent with a file-format parsing vulnerability triggered at file open time rather than a remotely reachable network service.
RemediationAI
The primary fix is to apply the vendor-released patch immediately. For Microsoft Access 2016 (both standard and 32-bit editions), upgrade to version 16.0.5565.1000 or later. For Microsoft Office 2019, LTSC 2021, LTSC 2024, and Microsoft 365 Apps for Enterprise, apply the latest update available at https://aka.ms/OfficeSecurityReleases. The MSRC advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-64914 should be the authoritative source for patch confirmation. As a compensating control where patching is not immediately possible, consider disabling or restricting the opening of Access database files (.accdb, .mdb) from untrusted or external sources via Group Policy or Protected View settings in Office. Enabling Microsoft Defender Application Guard or Attack Surface Reduction rules targeting Office file execution can reduce exploitation surface, though these controls add user friction. Do not rely on these workarounds as long-term mitigations.
Microsoft Outlook Remote Code Execution Vulnerability. Rated critical severity (CVSS 9.8), this vulnerability is remotel
Microsoft Excel Security Feature Bypass Vulnerability. Rated high severity (CVSS 7.8), this vulnerability is no authenti
Microsoft Outlook Security Feature Bypass Vulnerability. Rated high severity (CVSS 8.8), this vulnerability is remotely
Microsoft Publisher Security Feature Bypass Vulnerability. Rated high severity (CVSS 7.3), this vulnerability is low att
Microsoft Office contains a security feature bypass (CVE-2026-21509, CVSS 7.8) where reliance on untrusted inputs in sec
Microsoft Office Word contains a security decision bypass (CVE-2026-21514, CVSS 7.8) through reliance on untrusted input
Microsoft Office Access Connectivity Engine Remote Code Execution Vulnerability. Rated high severity (CVSS 7.8), this vu
Microsoft Office Remote Code Execution Vulnerability. Rated high severity (CVSS 7.8), this vulnerability is no authentic
Microsoft Excel Remote Code Execution Vulnerability. Rated high severity (CVSS 7.8), this vulnerability is no authentica
Use-after-free vulnerability in Microsoft Office Word that allows local, unauthenticated attackers to execute arbitrary
Microsoft Excel Remote Code Execution Vulnerability. Rated high severity (CVSS 8.8), this vulnerability is remotely expl
Microsoft Office Elevation of Privilege Vulnerability. Rated high severity (CVSS 7.8), this vulnerability is low attack
Same weakness CWE-122 – Heap-based Buffer Overflow
View allSame technique Buffer Overflow
View allShare
External POC / Exploit Code
Leaving vuln.today