CVE-2021-26421

Skype for Business and Lync Spoofing Vulnerability

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Published May 11, 2021 CVSS 3.1 · 6.5 Medium EPSS 1.4% KEV · Not listed

Description

Skype for Business and Lync Spoofing Vulnerability

Affected Products

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

Microsoft

Skype for Business Server 2015 CU11

affected

Version	Status	Constraints
`2015 CU11`	affected	< 2046.369

Microsoft

Microsoft Lync Server 2013 CU10

affected

Version	Status	Constraints
`8308.0`	affected	< 8308.1144

Configuration 1 [-]

OR	cpe:2.3:a:microsoft:lync_server:2013:cumulative_update_10::::::
	cpe:2.3:a:microsoft:skype_for_business_server:2015:cumulative_update_11::::::

No data.

No data available yet.

Remediation

No solution or workaround provided in the CVE record

Tracking

Sign in to view the affected projects.

Advisories

Source	ID	Title
EUVD	EUVD-2021-13227	Skype for Business and Lync Spoofing Vulnerability

Metrics

No CVSS v4.0

Attack Vector Network

Attack Complexity High

Privileges Required Low

Scope Changed

Confidentiality Impact High

Integrity Impact Low

Availability Impact None

User Interaction Required

No CVSS v3.0

Access Vector Network

Access Complexity Medium

Authentication None

Confidentiality Impact Partial

Integrity Impact Partial

Availability Impact None

This CVE is not in the KEV list.

Exploit prediction score: 1.4% (1.411% probability within 30 days)

Key SSVC decision points have not yet been added.

References

Link	Providers
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26421

History

No history.

Subscriptions

Microsoft Lync Server Skype For Business Server

Weaknesses

NVD-CWE-noinfo

Sources

CVE record Updated: Aug 3, 2024, 8:26 PM

Status: PUBLISHED
Assigner: microsoft
Published: May 11, 2021, 7:11 PM
Updated: Aug 3, 2024, 8:26 PM
Reserved: Jan 29, 2021, 12:00 AM

View source JSON

Vulnrichment No data

No data.

NVD Updated: Jun 17, 2026, 3:43 AM

Status: Modified
Published: May 11, 2021, 7:15 PM
Modified: Jun 17, 2026, 3:43 AM

View source JSON

Red Hat No data

No data.

OpenCVE enrichment No data

No data.

{"affected": [{"affectedData": [{"cpes": ["cpe:2.3:a:microsoft:skype_for_business_server:2015:cumulative_update_11:*:*:*:*:*:*"], "platforms": ["Unknown"], "product": "Skype for Business Server 2015 CU11", "vendor": "Microsoft", "versions": [{"lessThan": "2046.369", "status": "affected", "version": "2015 CU11", "versionType": "custom"}]}, {"cpes": ["cpe:2.3:a:microsoft:lync_server:2013:cumulative_update_10:*:*:*:*:*:*"], "platforms": ["Unknown"], "product": "Microsoft Lync Server 2013 CU10", "vendor": "Microsoft", "versions": [{"lessThan": "8308.1144", "status": "affected", "version": "8308.0", "versionType": "custom"}]}], "source": "secure@microsoft.com"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:microsoft:lync_server:2013:cumulative_update_10:*:*:*:*:*:*", "matchCriteriaId": "33F380C0-651D-4ACF-B729-8A05EC5D5AA4", "vulnerable": true}, {"criteria": "cpe:2.3:a:microsoft:skype_for_business_server:2015:cumulative_update_11:*:*:*:*:*:*", "matchCriteriaId": "E5E44D3D-AED8-4A45-8A48-3F21A7CE4D26", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "Skype for Business and Lync Spoofing Vulnerability"}, {"lang": "es", "value": "Una vulnerabilidad de Suplantaci\u00f3n de Identidad de Skype Business y Lync"}], "id": "CVE-2021-26421", "lastModified": "2026-06-17T03:43:22.813", "metrics": {"cvssMetricV2": [{"acInsufInfo": false, "baseSeverity": "MEDIUM", "cvssData": {"accessComplexity": "MEDIUM", "accessVector": "NETWORK", "authentication": "NONE", "availabilityImpact": "NONE", "baseScore": 5.8, "confidentialityImpact": "PARTIAL", "integrityImpact": "PARTIAL", "vectorString": "AV:N/AC:M/Au:N/C:P/I:P/A:N", "version": "2.0"}, "exploitabilityScore": 8.6, "impactScore": 4.9, "obtainAllPrivilege": false, "obtainOtherPrivilege": false, "obtainUserPrivilege": false, "source": "nvd@nist.gov", "type": "Primary", "userInteractionRequired": true}], "cvssMetricV31": [{"cvssData": {"attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 6.5, "baseSeverity": "MEDIUM", "confidentialityImpact": "HIGH", "integrityImpact": "LOW", "privilegesRequired": "LOW", "scope": "CHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:L/A:N", "version": "3.1"}, "exploitabilityScore": 1.3, "impactScore": 4.7, "source": "secure@microsoft.com", "type": "Secondary"}, {"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 7.1, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:N", "version": "3.1"}, "exploitabilityScore": 2.8, "impactScore": 4.2, "source": "nvd@nist.gov", "type": "Secondary"}]}, "published": "2021-05-11T19:15:08.870", "references": [{"source": "secure@microsoft.com", "tags": ["Patch", "Vendor Advisory"], "url": "https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26421"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Patch", "Vendor Advisory"], "url": "https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26421"}], "sourceIdentifier": "secure@microsoft.com", "vulnStatus": "Modified", "weaknesses": [{"description": [{"lang": "en", "value": "NVD-CWE-noinfo"}], "source": "nvd@nist.gov", "type": "Primary"}]}