CVE-2026-21258

Improper input validation in Microsoft Office Excel 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-2026-21258	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:excel:2016::::::x64:
	cpe:2.3:a:microsoft:excel:2016::::::x86:
	cpe:2.3:a:microsoft:office:2019::::::x64:
	cpe:2.3:a:microsoft:office:2019::::::x86:
	cpe:2.3:a:microsoft:office_long_term_servicing_channel:2021:::::-:x64:*
	cpe:2.3:a:microsoft:office_long_term_servicing_channel:2021:::::-:x86:*
	cpe:2.3:a:microsoft:office_long_term_servicing_channel:2021:::::macos::
	cpe:2.3:a:microsoft:office_long_term_servicing_channel:2024:::::-:x64:*
	cpe:2.3:a:microsoft:office_long_term_servicing_channel:2024:::::-:x86:*
	cpe:2.3:a:microsoft:office_long_term_servicing_channel:2024:::::macos::
	cpe:2.3:a:microsoft:office_online_server::::::::

History

No history.

Information

Published : 2026-02-10 18:16

Updated : 2026-02-11 19:12

NVD link : CVE-2026-21258

Mitre link : CVE-2026-21258

CVE.ORG link : CVE-2026-21258

JSON object : View

Products Affected

microsoft

excel
office
office_long_term_servicing_channel
office_online_server
365_apps

CWE

CWE-20

Improper Input Validation

CWE-125

Out-of-bounds Read

{"id": "CVE-2026-21258", "cveTags": [], "metrics": {"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}]}, "published": "2026-02-10T18:16:27.637", "references": [{"url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21258", "tags": ["Vendor Advisory"], "source": "secure@microsoft.com"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Secondary", "source": "secure@microsoft.com", "description": [{"lang": "en", "value": "CWE-20"}, {"lang": "en", "value": "CWE-125"}]}], "descriptions": [{"lang": "en", "value": "Improper input validation in Microsoft Office Excel allows an unauthorized attacker to disclose information locally."}, {"lang": "es", "value": "Validaci\u00f3n de entrada incorrecta en Microsoft Office Excel permite a un atacante no autorizado divulgar informaci\u00f3n localmente."}], "lastModified": "2026-02-11T19:12:56.623", "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:excel:2016:*:*:*:*:*:x64:*", "vulnerable": true, "matchCriteriaId": "CD88F667-6773-4DB7-B6C3-9C7B769C0808"}, {"criteria": "cpe:2.3:a:microsoft:excel:2016:*:*:*:*:*:x86:*", "vulnerable": true, "matchCriteriaId": "B342EF98-B414-44D0-BAFB-FCA24294EECE"}, {"criteria": "cpe:2.3:a:microsoft:office:2019:*:*:*:*:*:x64:*", "vulnerable": true, "matchCriteriaId": "CF5DDD09-902E-4881-98D0-CB896333B4AA"}, {"criteria": "cpe:2.3:a:microsoft:office:2019:*:*:*:*:*:x86:*", "vulnerable": true, "matchCriteriaId": "26A3B226-5D7C-4556-9350-5222DC8EFC2C"}, {"criteria": "cpe:2.3:a:microsoft:office_long_term_servicing_channel:2021:*:*:*:*:-:x64:*", "vulnerable": true, "matchCriteriaId": "851BAC4E-9965-4F40-9A6C-B73D9004F4C1"}, {"criteria": "cpe:2.3:a:microsoft:office_long_term_servicing_channel:2021:*:*:*:*:-:x86:*", "vulnerable": true, "matchCriteriaId": "23B2FA23-76F4-4D83-A718-B8D04D7EA37B"}, {"criteria": "cpe:2.3:a:microsoft:office_long_term_servicing_channel:2021:*:*:*:*:macos:*:*", "vulnerable": true, "matchCriteriaId": "BF0E8112-5B6F-4E55-8E40-38ADCF6FC654"}, {"criteria": "cpe:2.3:a:microsoft:office_long_term_servicing_channel:2024:*:*:*:*:-:x64:*", "vulnerable": true, "matchCriteriaId": "D31E509A-0B2E-4B41-88C4-0099E800AFE6"}, {"criteria": "cpe:2.3:a:microsoft:office_long_term_servicing_channel:2024:*:*:*:*:-:x86:*", "vulnerable": true, "matchCriteriaId": "017A7041-BEF1-4E4E-AC8A-EFC6AFEB01FE"}, {"criteria": "cpe:2.3:a:microsoft:office_long_term_servicing_channel:2024:*:*:*:*:macos:*:*", "vulnerable": true, "matchCriteriaId": "EF3E56B5-E6A6-4061-9380-D421E52B9199"}, {"criteria": "cpe:2.3:a:microsoft:office_online_server:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "0213E443-C4CD-41DC-9C07-B2D85B284389", "versionEndExcluding": "16.0.10417.20097"}], "operator": "OR"}]}], "sourceIdentifier": "secure@microsoft.com"}