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Full vulnerability report · 2019
CVE-2019-0798High confidence

Microsoft Skype for Business Server 2015: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Microsoft · Skype for Business Server 2015

6.1MediumCVSS 3.0
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 2.08% 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 Skype for Business Server 2015 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-2019-1554

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

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
Not supplied in the stored EUVD record
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

A spoofing vulnerability exists when a Lync Server or Skype for Business Server does not properly sanitize a specially crafted request, aka 'Skype for Business and Lync Spoofing Vulnerability'.

What

A spoofing vulnerability exists when a Lync Server or Skype for Business Server does not properly sanitize a specially crafted request, aka 'Skype for Business and Lync Spoofing Vulnerability'.

Why

Attacker-controlled content can reach a browser as executable script without sufficient output encoding or sanitisation.

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

A spoofing vulnerability exists when a Lync Server or Skype for Business Server does not properly sanitize a specially crafted request, aka 'Skype for Business and Lync Spoofing Vulnerability'.

Why

Attacker-controlled content can reach a browser as executable script without sufficient output encoding or sanitisation.

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 → Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') → 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
Changed: exploitation can affect a different security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-79 ↗

CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'). The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Common Vulnerability Scoring System 3.0: 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.SChangedScope: The attack can affect a component governed by a different security authority.CLowConfidentiality impact: A successful attack can cause a limited loss.ILowIntegrity impact: A successful attack can cause a limited loss.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-79
A

Official authority intelligence

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

CERT-FR · French · CERTFR-2019-AVI-106Multiples vulnérabilités dans les produits Microsoft

De multiples vulnérabilités ont été corrigées dans les produits Microsoft . Elles permettent à un attaquant de provoquer une élévation de privilèges, une atteinte à la confidentialité des données, une exécution de code à distance, une usurpation d'identité et un contournement de la fonctionnalité de sécurité.

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2019-002539Lync Server および Skype for Business におけるなりすましの脆弱性

Lync Server および Skype for Business Server には、巧妙に細工された要求を適切にサニタイズしない場合、なりすましの脆弱性が存在します。 ベンダは、本脆弱性を「Skype for Business および Lync のなりすましの脆弱性」として公開しています。

Official advisory ↗
KISA KrCERT/CC · Korean · KNVD-5004MS 3월 보안 위협에 따른 정기 보안 업데이트 권고

- DID 취약점(CVE-2019-0798)

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 9 Apr 2019 · Last source change 4 Aug 2024, 17:58 UTC · CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

CVE recordCVE.org · 5.1
CVSS sourceNIST NVD
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-09-01
European sourceENISA EUVD · EUVD-2019-1554
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceNIST NVD
NVD statusNVD modified after enrichment

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

Material change intelligence

What changed after publication

View recent updates ↗
  1. ENISA EUVD mappingEUVD-2019-1554 was added to the official ENISA EUVD mapping for this CVE.
    Before
    not recorded
    After
    {"euvdId":"EUVD-2019-1554"}
    ENISA EUVD ↗
  2. Vendor guidanceAuthoritative vendor guidance changed: added patch: portal.msrc.microsoft.com/CVE-2019-0798; added remediation: portal.msrc.microsoft.com/CVE-2019-0798.
    Before
    no authoritative guidance recorded
    After
    patch: portal.msrc.microsoft.com/CVE-2019-0798 · remediation: portal.msrc.microsoft.com/CVE-2019-0798
    portal.msrc.microsoft.com ↗
  3. Affected versionsThe structured affected or fixed version information changed.
    Before
    March 2019 Update; July 2018 Update · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    March 2019 Update; July 2018 Update · 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 ↗
  4. Remediation statusRemediation status changed from Awaiting fix to Patch available.
    Before
    Awaiting fix
    After
    Patch available
    portal.msrc.microsoft.com ↗
  5. SeveritySeverity changed from Unknown to Medium.
    Before
    Unknown
    After
    Medium
    NIST NVD ↗
  6. CVSS scoreCVSS score changed from not recorded to 6.1 (CVSS 3.0 · NIST NVD · CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N).
    Before
    not recorded
    After
    6.1 (CVSS 3.0 · NIST NVD · CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N)
    NIST NVD ↗
  7. 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-2019-1554↗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-2019-0798 · cve.blacktree.nl