CVE-2026-66304: Skype for Business Information Disclosure Vulnerability

Recommended actionWithin 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available

What, why and how

Server-side request forgery (ssrf) in Skype for Business allows an unauthorized attacker to disclose information over a network.

What

Server-side request forgery (ssrf) in Skype for Business allows an unauthorized attacker to disclose information over a network.

Why

The server follows an attacker-influenced destination, allowing requests to systems or services the attacker cannot reach directly.

How

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

What

Server-side request forgery (ssrf) in Skype for Business allows an unauthorized attacker to disclose information over a network.

Why

The server follows an attacker-influenced destination, allowing requests to systems or services the attacker cannot reach directly.

How

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 → Server-Side Request Forgery (SSRF) → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface: Network
Privileges required: None: unauthenticated exploitation is possible
User interaction: None
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-918 ↗
CWE-918: Server-Side Request Forgery (SSRF). The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.
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:N/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.UINoneUser interaction: No action by another user is required.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-918

Official authority intelligence

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

ENISA EUVD · EUVD-2026-74043Official EUVD mapping

Server-side request forgery (ssrf) in Skype for Business 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-1149Multiples vulnérabilités dans les produits Microsoft

septembre 2026 Bulletin de sécurité Microsoft CVE-2026-58600 du 08 septembre 2026 Bulletin de sécurité Microsoft CVE-2026-58611 du 08 septembre 2026 Bulletin de sécurité Microsoft CVE-2026-58649 du 08 septembre 2026 Bulletin de sécurité Microsoft CVE-2026-63523 du 08 septembre 2026 Bulletin de sécurité Microsoft CVE-2026-65669 du 08 septembre 2026 Bulletin de sécurité Microsoft CVE-2026-65772 du 08 septembre 2026 Bulletin de sécurité Microsoft CVE-2026-65812 du 08 septembre 2026 Bulletin de sécurité Microsoft CVE-2026-66302 du 08 septembre 2026 Bulletin de sécurité Microsoft CVE-2026-66303 du 08 septembre 2026 Bulletin de sécurité Microsoft CVE-2026-66304 du 08 septembre 2026 Bulletin de sécurité Microsoft CVE-2026-66305 du 08 septembre 2026 Bulletin de sécurité Microsoft CVE-2026-66306 du 08 septembre 2026 Bulletin de sécurité Microsoft CVE-2026-66307 du 08 septembre 2026 Bulletin de sécurité Microsoft CVE-2026-66308 du 08 septembre 2026 Bulletin de sécurité Microsoft CVE-2026-66814 du 08 septembre 2026 Bulletin de sécurité Microsoft CVE-2026-66816 du 08 septembre 2026 Bulletin de sécurité Microsoft CVE-2026-66818 du 08 septembre 2026 Bulletin de sécurité Microsoft CVE-2026-66819 du 08 septembre 2026 Bulletin de sécurité Microsoft CVE-2026-66820 du 08 septembre 2026 Bulletin de sécurité Micr

Official advisory ↗

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

nuova finestra - - CVE-2026-68846 : apre una nuova finestra - - CVE-2026-66307 : apre una nuova finestra - - CVE-2026-67638 : apre una nuova finestra - - CVE-2026-68847 : apre una nuova finestra - - CVE-2026-56198 : apre una nuova finestra - - CVE-2026-68840 : apre una nuova finestra - - CVE-2026-68841 : apre una nuova finestra - - CVE-2026-67631 : apre una nuova finestra - - CVE-2026-67630 : apre una nuova finestra - - CVE-2026-62744 : apre una nuova finestra - - CVE-2026-66302 : apre una nuova finestra - - CVE-2026-67633 : apre una nuova finestra - - CVE-2026-68844 : apre una nuova finestra - - CVE-2026-68845 : apre una nuova finestra - - CVE-2026-66304 : apre una nuova finestra - - CVE-2026-68842 : apre una nuova finestra - - CVE-2026-66303 : apre una nuova finestra - - CVE-2026-68843 : apre una nuova finestra - - CVE-2026-64918 : apre una nuova finestra - - CVE-2026-56177 : apre una nuova finestra - - CVE-2026-58599 : apre una nuova finestra - - CVE-2026-68837 : apre una nuova finestra - - CVE-2026-68838 : apre una nuova finestra - - CVE-2026-68835 : apre una nuova finestra - - CVE-2026-67629 : apre una nuova finestra - - CVE-2026-68839 : apre una nuova finestra - - CVE-2026-68830 : apre una nuova finestra - - CVE-2026-68833 : apre una nuova finestra - - CVE-2026-68834 : apre una nuova fi

Official advisory ↗

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

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 ↗

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: Skype for Business Server 2015 CU13: 9319.0 < 6.0.9319.885
Skype for Business Server 2019 CU8: 2046.0 < 7.0.2046.569
Skype for Business Server Subscription Edition CU1: 2046.0 < 7.0.2046.879
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.

Evidence and provenance

Published 8 Sept 2026 · Last source change 11 Sept 2026, 22:08 UTC · CWE-918 · Server-Side Request Forgery (SSRF)

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-2026-74043

Product sourceCNA

Remediation sourceCVE/CNA references

CWE sourceOther authority

NVD statusNVD enrichment underway

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

Material change intelligence

What changed after publication

View recent updates ↗

11 Sept 2026, 22:08 UTC
Affected versionsThe structured affected or fixed version information changed.
Before
9319.0 < 6.0.9319.885; 2046.0 < 7.0.2046.569; 2046.0 < 7.0.2046.879 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
After
Skype for Business Server 2015 CU13: 9319.0 < 6.0.9319.885; Skype for Business Server 2019 CU8: 2046.0 < 7.0.2046.569; Skype for Business Server Subscription Edition CU1: 2046.0 < 7.0.2046.879 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
CNA ↗
9 Sept 2026, 15:04 UTC
ENISA EUVD mappingEUVD-2026-74043 was added to the official ENISA EUVD mapping for this CVE.
Before
not recorded
After
{"euvdId":"EUVD-2026-74043"}
ENISA EUVD ↗
8 Sept 2026, 18:30 UTC
Catalogue recordCVE added to the BlackTree catalogue.
CNA ↗

2026-09-08CVE published

ENISA EUVD · EUVD-2026-74043↗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.

Skype for Business Information Disclosure Vulnerability

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

ENISA European Vulnerability Database

EUVD-2026-74043

What, why and how

Exploit reality and attack path

Official authority intelligence

Patch and workaround

Evidence and provenance

What changed after publication

Skype for Business Information Disclosure Vulnerability

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

EUVD-2026-74043

What, why and how

Exploit reality and attack path

Official authority intelligence

Patch and workaround

Evidence and provenance

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