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Full vulnerability report · 2026
CVE-2026-80087High confidence

Microsoft Office Information Disclosure Vulnerability

Microsoft · Microsoft 365 Apps for Enterprise

6.5MediumCVSS 3.1
Recommended action
Scheduled

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityMediumOperational priority:Medium, unchanged from published severity.unchanged

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • EPSS is 0.92% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict the affected network interface to trusted sources where business-safe.
  • Monitor vendor guidance and exploitation sources for a material change.

Verification

  1. Confirm that the asset runs Microsoft Microsoft 365 Apps for Enterprise and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: As exposure requiresRemediation target: Within 365 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2026-73839

No EUVD known-exploited evidence

Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to disclose information over a network.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
6.5 · CVSS 3.1
Advisory evidence
No linked advisory details stored yet
Recommended actionScheduled

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.

Patch available
01

What, why and how

Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to disclose information over a network.

What

Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to disclose information over a network.

Why

A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().

How

An attacker operating through a network path may attempt exploitation without authentication after a user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to disclose information over a network.

Why

A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().

How

An attacker operating through a network path may attempt exploitation without authentication after a user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
a network path → Heap-based Buffer Overflow → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
Required interaction required
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-122 ↗

CWE-122: Heap-based Buffer Overflow. A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UIRequiredUser interaction: Another user must perform an action for exploitation to succeed.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.INoneIntegrity impact: No direct loss is represented by this metric.ANoneAvailability impact: No direct loss is represented by this metric.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedCWE-122
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2026-73839Official EUVD mapping

Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to disclose information over a network.

Official EUVD record ↗
BSI · German · WID-SEC-2026-3234Microsoft Office Produkte: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in verschiedenen Microsoft Office Produkten, Microsoft Office Online Server, Microsoft 365 Apps, Microsoft SharePoint, Microsoft Teams und Microsoft Skype ausnutzen, um erhöhte Berechtigungen zu erlangen, um Code auszuführen, um Informationen offenzulegen und um den Nutzer zu täuschen.

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-1145Multiples vulnérabilités dans Microsoft Office

u 08 septembre 2026 Bulletin de sécurité Microsoft Office CVE-2026-80078 du 08 septembre 2026 Bulletin de sécurité Microsoft Office CVE-2026-80079 du 08 septembre 2026 Bulletin de sécurité Microsoft Office CVE-2026-80080 du 08 septembre 2026 Bulletin de sécurité Microsoft Office CVE-2026-80081 du 08 septembre 2026 Bulletin de sécurité Microsoft Office CVE-2026-80082 du 08 septembre 2026 Bulletin de sécurité Microsoft Office CVE-2026-80084 du 08 septembre 2026 Bulletin de sécurité Microsoft Office CVE-2026-80085 du 08 septembre 2026 Bulletin de sécurité Microsoft Office CVE-2026-80086 du 08 septembre 2026 Bulletin de sécurité Microsoft Office CVE-2026-80087 du 08 septembre 2026 Bulletin de sécurité Microsoft Office CVE-2026-80088 du 08 septembre 2026 Bulletin de sécurité Microsoft Office CVE-2026-80089 du 08 septembre 2026 Bulletin de sécurité Microsoft Office CVE-2026-80090 du 08 septembre 2026 Bulletin de sécurité Microsoft Office CVE-2026-80091 du 08 septembre 2026 Bulletin de sécurité Microsoft Office CVE-2026-81385 du 08 septembre 2026 Bulletin de sécurité Microsoft Office CVE-2026-81386 du 08 septembre 2026 Bulletin de sécurité Microsoft Office CVE-2026-81387 du 08 septembre 2026 Bulletin de sécurité Microsoft Office CVE-2026-81388 du 08 septembre 2026 Bulletin de sécurité Microsoft Offic

Official advisory ↗
CSIRT Italia · Italian · aggiornamenti-mensili-microsoft-24Aggiornamenti Mensili Microsoft

nuova finestra - - CVE-2026-78444 : apre una nuova finestra - - CVE-2026-78445 : apre una nuova finestra - - CVE-2026-78446 : apre una nuova finestra - - CVE-2026-80090 : apre una nuova finestra - - CVE-2026-78447 : apre una nuova finestra - - CVE-2026-78448 : apre una nuova finestra - - CVE-2026-80082 : apre una nuova finestra - - CVE-2026-80083 : apre una nuova finestra - - CVE-2026-83990 : apre una nuova finestra - - CVE-2026-80080 : apre una nuova finestra - - CVE-2026-83991 : apre una nuova finestra - - CVE-2026-80081 : apre una nuova finestra - - CVE-2026-83992 : apre una nuova finestra - - CVE-2026-80086 : apre una nuova finestra - - CVE-2026-80087 : apre una nuova finestra - - CVE-2026-78450 : apre una nuova finestra - - CVE-2026-80084 : apre una nuova finestra - - CVE-2026-78451 : apre una nuova finestra - - CVE-2026-80085 : apre una nuova finestra - - CVE-2026-83997 : apre una nuova finestra - - CVE-2026-83998 : apre una nuova finestra - - CVE-2026-80088 : apre una nuova finestra - - CVE-2026-83999 : apre una nuova finestra - - CVE-2026-80089 : apre una nuova finestra - - CVE-2026-83995 : apre una nuova finestra - - CVE-2026-83996 : apre una nuova finestra - - Change log Titolo della tabella Versione Note Data 1.0 Pubblicato il 09-09-2026 09/09/2026 1.1 Aggiunta descrizione di 2 RCE

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2026-033153マイクロソフトのMicrosoft 365 Apps等の複数製品におけるヒープベースのバッファオーバーフローの脆弱性

Microsoft Officeにおけるヒープベースのバッファオーバーフローにより、権限のない攻撃者がネットワーク経由で情報を開示できる可能性があります。

Official advisory ↗
KISA KrCERT/CC · Korean · KNVD-6946MS 9월 보안 위협에 따른 정기 보안 업데이트 권고

soft Office Word | CVE-2026-80079 | Microsoft Office Word 정보 공개 취약성 | | Microsoft Office Word | CVE-2026-80080 | Microsoft Office Word 원격 코드 실행 취약성 | | Microsoft Office PowerPoint | CVE-2026-80081 | Microsoft Office PowerPoint 원격 코드 실행 취약성 | | Microsoft Office | CVE-2026-80082 | Microsoft Office 정보 유출 취약성 | | Windows Hyper-V | CVE-2026-80083 | Windows Hyper-V 원격 코드 실행 취약성 | | Microsoft Office Outlook | CVE-2026-80084 | Microsoft Office Outlook 정보 유출 취약성 | | Microsoft Office Word | CVE-2026-80085 | Microsoft Office Word 원격 코드 실행 취약성 | | Microsoft Office PowerPoint | CVE-2026-80086 | Microsoft Office PowerPoint 정보 유출 취약성 | | Microsoft Office | CVE-2026-80087 | Microsoft Office 정보 유출 취약성 | | Microsoft Office Word | CVE-2026-80088 | Microsoft Office Word 정보 공개 취약성 | | Microsoft Office | CVE-2026-80089 | Microsoft Office 정보 유출 취약성 | | Microsoft Office Word | CVE-2026-80090 | Microsoft Office Word 정보 공개 취약성 | | Microsoft Office | CVE-2026-80091 | Microsoft Office 정보 유출 취약성 | | Windows Cloud Files Mini Filter Driver | CVE-2026-80093 | Windows 클라우드 파일 미니 필터 드라이버 권한 상승 취약성 | | Windows Remote Desktop Services | CVE-2026-80096 | Windows 원격 데스크톱 서비스 권한 상승 취약성 | | Microsoft Authenticator | CVE-2026-80097 | Microsoft Authenticator 권한 상승 취약성 | | Copilot Studio | CVE-2026-80098 | Copilot Studio 권한 상승 취약성 | |

Official advisory ↗
NCSC-NL · Dutch · NCSC-2026-0352Kwetsbaarheden verholpen in Microsoft Office

Een kwaadwillende kan de kwetsbaarheden misbruiken om aanvallen uit te voeren die kunnen leiden tot de categorieën schade, zoals genoemd in onderstaande tabel. Voor succesvol misbruik moet de kwaadwillende het slachtoffer misleiden een malafide bestand te openen of link te volgen. Microsoft heeft voor Office 114 kwetsbaarheden verholpen. De 4 ernstigste kwetsbaarheden bevinden zich in meerdere Office componenten en hebben een CVSS score van 9.8 toegewezen gekregen. Kwaadwillenden met toegang tot deze componenten kunnen zonder voorafgaande authenticatie mogelijk code uitvoeren of zich toegang verschaffen tot het kwetsbare systeem. Deze kwetsbaarheden zijn in onderstaande tabel weergegeven. De overige 110 kwetsbaarheden variëren in ernst van middelmatig tot hoog en kritiek. Raapleeg het MSRC-portaal voor aanvullende informatie. ``` |----------------|------|---------------------------|-------------------------------------| | CVE-ID | CVSS | Component | Impact | |----------------|------|---------------------------|-------------------------------------| | CVE-2026-78505 | 9,80 | Office | Uitvoeren van willekeurige code | |----------------|------|---------------------------|-------------------------------------| | CVE-2026-78509 | 9,80 | Outlook | Uitvoeren van willekeurige code | |----------------|------|---------------------------|-------------------------------------| | CVE-2026-78510 | 9,80 | Outlook | Uitvoeren van willekeurige code | |----------------|------|---------------------------|-------------------------------------| | CVE-2026-66302 | 9,80 | SKYPE | Uitvoeren van willekeurige code | |----------------|------|---------------------------|-------------------------------------| ```

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
Fixed
An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
Action
Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 8 Sept 2026 · Last source change 1 Oct 2026, 23:00 UTC · CWE-122 · Heap-based Buffer Overflow

CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-09-09
European sourceENISA EUVD · EUVD-2026-73839
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceOther authority
NVD statusNVD enriched

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Affected versionsThe structured affected or fixed version information changed.
    Before
    Microsoft 365 Apps for Enterprise: 16.0.1 < 16.0.20326.20138; Microsoft Office 2016: 16.0.0 < 16.0.5569.1000; Microsoft Office 2019: 19.0.0 < 16.0.10417.20207; Microsoft Office 365 for Mac: -; Microsoft Office LTSC 2021: 16.0.1 < 16.0.14334.20906; Microsoft Office LTSC 2024: 16.0.0 < 16.0.17932.20976; Microsoft Office LTSC for Mac 2021: -; Microsoft Office LTSC for Mac 2024: - · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
    After
    Microsoft 365 Apps for Enterprise: 16.0.1 < 16.0.20326.20138; Microsoft Office 2016: 16.0.0 < 16.0.5569.1000; Microsoft Office 2019: 19.0.0 < 16.0.10417.20207; Microsoft Office 365 for Mac: 1.0.0 < 16.113.26091433; Microsoft Office LTSC 2021: 16.0.1 < 16.0.14334.20906; Microsoft Office LTSC 2024: 16.0.0 < 16.0.17932.20976; Microsoft Office LTSC for Mac 2021: 16.0.1 < 16.113.26091433; Microsoft Office LTSC for Mac 2024: 16.0.0 < 16.113.26091433 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
    CNA ↗
  2. Affected versionsThe structured affected or fixed version information changed.
    Before
    16.0.1 < 16.0.20326.20138; 16.0.0 < 16.0.5569.1000; 19.0.0 < 16.0.10417.20207; -; 16.0.1 < 16.0.14334.20906; 16.0.0 < 16.0.17932.20976 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
    After
    Microsoft 365 Apps for Enterprise: 16.0.1 < 16.0.20326.20138; Microsoft Office 2016: 16.0.0 < 16.0.5569.1000; Microsoft Office 2019: 19.0.0 < 16.0.10417.20207; Microsoft Office 365 for Mac: -; Microsoft Office LTSC 2021: 16.0.1 < 16.0.14334.20906; Microsoft Office LTSC 2024: 16.0.0 < 16.0.17932.20976; Microsoft Office LTSC for Mac 2021: -; Microsoft Office LTSC for Mac 2024: - · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
    CNA ↗
  3. Vendor guidanceAuthoritative vendor guidance changed: added patch: msrc.microsoft.com/CVE-2026-80087; added remediation: msrc.microsoft.com/CVE-2026-80087.
    Before
    no authoritative guidance recorded
    After
    patch: msrc.microsoft.com/CVE-2026-80087 · remediation: msrc.microsoft.com/CVE-2026-80087
    secure@microsoft.com ↗
  4. Affected versionsThe structured affected or fixed version information changed.
    Before
    16.0.1 < 16.0.20326.20138; 16.0.0 < 16.0.5569.1000; 19.0.0 < 16.0.10417.20207; -; 16.0.1 < 16.0.14334.20906; 16.0.0 < 16.0.17932.20976 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    16.0.1 < 16.0.20326.20138; 16.0.0 < 16.0.5569.1000; 19.0.0 < 16.0.10417.20207; -; 16.0.1 < 16.0.14334.20906; 16.0.0 < 16.0.17932.20976 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
    CNA ↗
  5. Remediation statusRemediation status changed from Awaiting fix to Patch available.
    Before
    Awaiting fix
    After
    Patch available
    secure@microsoft.com ↗
  6. ENISA EUVD mappingEUVD-2026-73839 was added to the official ENISA EUVD mapping for this CVE.
    Before
    not recorded
    After
    {"euvdId":"EUVD-2026-73839"}
    ENISA EUVD ↗
  7. Affected versionsThe structured affected or fixed version information changed.
    Before
    16.0.1 < 16.0.20326.20136; 16.0.0 < 16.0.5569.1000; 19.0.0 < 16.0.10417.20204; -; 16.0.1 < 16.0.14334.20896; 16.0.0 < 16.0.17932.20960 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    16.0.1 < 16.0.20326.20138; 16.0.0 < 16.0.5569.1000; 19.0.0 < 16.0.10417.20207; -; 16.0.1 < 16.0.14334.20906; 16.0.0 < 16.0.17932.20976 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    CNA ↗
  8. Catalogue recordCVE added to the BlackTree catalogue.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
ENISA EUVD · EUVD-2026-73839↗CVE authority or vendor reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2026-80087 · cve.blacktree.nl