CVE-2026-66809

Out-of-bounds read in Microsoft Office allows an unauthorized attacker to disclose information locally.

CVSS v3 5.5 MEDIUM

5.5^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 1.8 / Impact : 3.6

Attack Vector LOCAL

Attack Complexity LOW

Privileges Required NONE

User Interaction REQUIRED

Confidentiality Impact HIGH

Integrity Impact NONE

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-66809	Vendor Advisory

Configurations

Configuration 1 (hide)

OR	cpe:2.3:a:microsoft:365_apps:-::::enterprise::x64:*
	cpe:2.3:a:microsoft:365_apps:-::::enterprise::x86:*
	cpe:2.3:a:microsoft:microsoft_365:-:::::macos::
	cpe:2.3:a:microsoft:office_2019:-::::::x64:
	cpe:2.3:a:microsoft:office_2019:-::::::x86:
	cpe:2.3:a:microsoft:office_2021:-::::ltsc:-:x64:
	cpe:2.3:a:microsoft:office_2021:-::::ltsc:-:x86:
	cpe:2.3:a:microsoft:office_2021:-::::ltsc:macos:-:
	cpe:2.3:a:microsoft:office_2024:-::::ltsc:-:x64:
	cpe:2.3:a:microsoft:office_2024:-::::ltsc:-:x86:
	cpe:2.3:a:microsoft:office_2024:-::::ltsc:macos:-:
	cpe:2.3:a:microsoft:word:2016::::::x64:
	cpe:2.3:a:microsoft:word:2016::::::x86:

History

No history.

Information

Published : 2026-08-11 17:19

Updated : 2026-08-14 17:42

NVD link : CVE-2026-66809

Mitre link : CVE-2026-66809

CVE.ORG link : CVE-2026-66809

JSON object : View

Products Affected

microsoft

office_2024
office_2019
microsoft_365
365_apps
office_2021
word

CWE

CWE-125

Out-of-bounds Read

{"id": "CVE-2026-66809", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-66809", "role": "CISA Coordinator", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "version": "2.0.3", "timestamp": "2026-08-13T13:43:25.725249Z"}}], "cvssMetricV31": [{"type": "Secondary", "source": "secure@microsoft.com", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 5.5, "attackVector": "LOCAL", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N", "integrityImpact": "NONE", "userInteraction": "REQUIRED", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "NONE", "confidentialityImpact": "HIGH"}, "impactScore": 3.6, "exploitabilityScore": 1.8}, {"type": "Primary", "source": "nvd@nist.gov", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 5.5, "attackVector": "LOCAL", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "LOW", "confidentialityImpact": "HIGH"}, "impactScore": 3.6, "exploitabilityScore": 1.8}]}, "affected": [{"source": "secure@microsoft.com", "affectedData": [{"vendor": "Microsoft", "product": "Microsoft 365 Apps for Enterprise", "versions": [{"status": "affected", "version": "16.0.1", "lessThan": "https://aka.ms/OfficeSecurityReleases", "versionType": "custom"}], "platforms": ["32-bit Systems", "x64-based Systems"]}, {"vendor": "Microsoft", "product": "Microsoft Office 2019", "versions": [{"status": "affected", "version": "19.0.0", "lessThan": "https://aka.ms/OfficeSecurityReleases", "versionType": "custom"}], "platforms": ["32-bit Systems", "x64-based Systems"]}, {"vendor": "Microsoft", "product": "Microsoft Office 365 for Mac", "versions": [{"status": "affected", "version": "1.0.0", "lessThan": "16.112.26081010", "versionType": "custom"}]}, {"vendor": "Microsoft", "product": "Microsoft Office LTSC 2021", "versions": [{"status": "affected", "version": "16.0.1", "lessThan": "https://aka.ms/OfficeSecurityReleases", "versionType": "custom"}], "platforms": ["32-bit Systems", "x64-based Systems"]}, {"vendor": "Microsoft", "product": "Microsoft Office LTSC 2024", "versions": [{"status": "affected", "version": "16.0.0", "lessThan": "https://aka.ms/OfficeSecurityReleases", "versionType": "custom"}], "platforms": ["32-bit Systems", "x64-based Systems"]}, {"vendor": "Microsoft", "product": "Microsoft Office LTSC for Mac 2021", "versions": [{"status": "affected", "version": "16.0.1", "lessThan": "16.112.26081010", "versionType": "custom"}]}, {"vendor": "Microsoft", "product": "Microsoft Office LTSC for Mac 2024", "versions": [{"status": "affected", "version": "16.0.0", "lessThan": "16.112.26081010", "versionType": "custom"}]}, {"vendor": "Microsoft", "product": "Microsoft Word 2016", "versions": [{"status": "affected", "version": "16.0.1", "lessThan": "16.0.5565.1000", "versionType": "custom"}], "platforms": ["32-bit Systems", "x64-based Systems"]}]}], "published": "2026-08-11T17:19:02.360", "references": [{"url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-66809", "tags": ["Vendor Advisory"], "source": "secure@microsoft.com"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Secondary", "source": "secure@microsoft.com", "description": [{"lang": "en", "value": "CWE-125"}]}], "descriptions": [{"lang": "en", "value": "Out-of-bounds read in Microsoft Office allows an unauthorized attacker to disclose information locally."}], "lastModified": "2026-08-14T17:42:31.713", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:x64:*", "vulnerable": true, "matchCriteriaId": "3259EBFE-AE2D-48B8-BE9A-E22BBDB31378"}, {"criteria": "cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:x86:*", "vulnerable": true, "matchCriteriaId": "CD25F492-9272-4836-832C-8439EBE64CCF"}, {"criteria": "cpe:2.3:a:microsoft:microsoft_365:-:*:*:*:*:macos:*:*", "vulnerable": true, "matchCriteriaId": "12418BDE-FA2E-4BBF-8E47-45C505399898"}, {"criteria": "cpe:2.3:a:microsoft:office_2019:-:*:*:*:*:*:x64:*", "vulnerable": true, "matchCriteriaId": "241CDE2B-ABD0-4EFF-8D73-1766E32FA20F"}, {"criteria": "cpe:2.3:a:microsoft:office_2019:-:*:*:*:*:*:x86:*", "vulnerable": true, "matchCriteriaId": "14D63E3F-A431-4DD8-979F-811E8DAC423D"}, {"criteria": "cpe:2.3:a:microsoft:office_2021:-:*:*:*:ltsc:-:x64:*", "vulnerable": true, "matchCriteriaId": "1D518075-3362-4D15-93B1-0E6C61518D16"}, {"criteria": "cpe:2.3:a:microsoft:office_2021:-:*:*:*:ltsc:-:x86:*", "vulnerable": true, "matchCriteriaId": "1059BEC6-C30B-4F0F-A878-5267A21CBD85"}, {"criteria": "cpe:2.3:a:microsoft:office_2021:-:*:*:*:ltsc:macos:-:*", "vulnerable": true, "matchCriteriaId": "0DB3EBBF-E0C4-4D5A-8D22-107463AD1DE4"}, {"criteria": "cpe:2.3:a:microsoft:office_2024:-:*:*:*:ltsc:-:x64:*", "vulnerable": true, "matchCriteriaId": "55A9AFDA-D77B-4CC7-ACE5-3A2ABDA257D8"}, {"criteria": "cpe:2.3:a:microsoft:office_2024:-:*:*:*:ltsc:-:x86:*", "vulnerable": true, "matchCriteriaId": "8887D177-26A3-4008-89B6-50A9E9830F13"}, {"criteria": "cpe:2.3:a:microsoft:office_2024:-:*:*:*:ltsc:macos:-:*", "vulnerable": true, "matchCriteriaId": "589B470B-9C2E-41E2-A44D-D8CCB4D2F933"}, {"criteria": "cpe:2.3:a:microsoft:word:2016:*:*:*:*:*:x64:*", "vulnerable": true, "matchCriteriaId": "E1FE9E95-4874-46EF-AC93-9E485F7A2AC0"}, {"criteria": "cpe:2.3:a:microsoft:word:2016:*:*:*:*:*:x86:*", "vulnerable": true, "matchCriteriaId": "38479B5D-66F9-4260-A18A-F6E3D9B6991E"}], "operator": "OR"}]}], "sourceIdentifier": "secure@microsoft.com"}