What is the CVSS score of CVE-2018-8311?

CVE-2018-8311 has a CVSS 3.0 base score of 8.8 (High). CVSS vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H. EPSS exploitation probability: 16.6%.

Skype For Business CVE-2018-8311

HIGH

Improper Input Validation (CWE-20)

2018-07-11 secure@microsoft.com

RCE Microsoft Lync Skype For Business

8.8

CVSS 3.0 · NVD

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Vulnerability Assessment

Weakness	CWE CWE-20 OWASP Top 10:2025 A05:2025 - Injection ASVS 5.0 V2 - Validation and Business Logic Input validation, allowlisting
Impact	CVSS score of 8.8 (HIGH). Attack characteristics: network attack vector, low complexity, no privileges required, user interaction required.
Exploit ScenarioDerived	This vulnerability can be exploited remotely over the network. Successful exploitation could compromise the high-severity affected system.

This Week Schedule remediation this week. Why: HIGH severity + EPSS > 10%.

No patch listed yet 16.6% exploitation probability (EPSS)

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AnalysisAI

A remote code execution vulnerability exists when Skype for Business and Microsoft Lync clients fail to properly sanitize specially crafted content, aka "Remote Code Execution Vulnerability in Skype. Rated high severity (CVSS 8.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.

Affects your stack

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Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability is classified under CWE-20. A remote code execution vulnerability exists when Skype for Business and Microsoft Lync clients fail to properly sanitize specially crafted content, aka "Remote Code Execution Vulnerability in Skype For Business and Lync." This affects Skype, Microsoft Lync. Affected products include: Microsoft Lync, Microsoft Skype For Business.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 8.8 HIGH

AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

DescriptionNVD

A remote code execution vulnerability exists when Skype for Business and Microsoft Lync clients fail to properly sanitize specially crafted content, aka "Remote Code Execution Vulnerability in Skype For Business and Lync." This affects Skype, Microsoft Lync.

Threat Intelligence Overview

EPSS Score

16.6%

Top 3% exploitable

Data Quality

2 sources

Confidence: Low

NVD

CVE.org

EPSS

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity HIGH

CISA KEV No

Public POC No

EPSS 16.6%

Patch available No

Active threat No

Deciding rule

HIGH severity + EPSS > 10%

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Scheduled

Exploitation· derived

None

System Exposure· derived

Open

Automatable· derived

Human Impact· derived

Medium

Priority Score

Low Medium High Critical

KEV: 0

EPSS: +17

CVSS: +44

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Remote Code Execution CRITICAL

Remote Code Execution represents the critical moment when an attacker successfully runs arbitrary code on a target system without physical access.

Affected Products (CPE)NVD

cpe:2.3:a:microsoft:lync:-:sp1:*:*:*:*:*:*

cpe:2.3:a:microsoft:skype_for_business:-:*:*:*:*:*:*:*

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Same weakness CWE-20 – Improper Input Validation

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References

Advisories & patches

ADVISORY https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2018-8311 REF http://www.securityfocus.com/bid/104624 REF http://www.securitytracker.com/id/1041259 REF http://www.securitytracker.com/id/1041260

Search Externally

GitHub PoC

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