What is the CVSS score of CVE-2021-43549?

CVE-2021-43549 has a CVSS 3.1 base score of 4.8 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N. EPSS exploitation probability: 0.7%.

Pi Web Api CVE-2021-43549

MEDIUM

Cross-site Scripting (XSS) (CWE-79)

2021-11-18 ics-cert@hq.dhs.gov

XSS Pi Web Api Osisoft

4.8

CVSS 3.1 · NVD

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Vulnerability Assessment

Weakness	CWE CWE-79 OWASP Top 10:2025 A05:2025 - Injection ASVS 5.0 V1 - Encoding and Sanitization Output encoding, context-aware escaping MITRE ATT&CK 2 techniques across 2 tactics: Initial Access, Execution The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. Sign in to read
Impact	CVSS score of 4.8 (MEDIUM). Attack characteristics: network attack vector, low complexity, high privileges required, user interaction required.
Exploit ScenarioDerived	A remote attacker could inject malicious scripts into web pages viewed by other users by sending crafted requests to the affected application.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).

No patch listed yet 0.7% exploitation probability (EPSS)

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AnalysisAI

A remote authenticated attacker with write access to a PI Server could trick a user into interacting with a PI Web API endpoint and redirect them to a malicious website. Rated medium severity (CVSS 4.8), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Sanitize all user input, use Content-Security-Policy headers, encode output contextually (HTML, JS, URL). Use frameworks with built-in XSS protection.

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 as Cross-Site Scripting (XSS) (CWE-79), which allows attackers to inject malicious scripts into web pages viewed by other users. A remote authenticated attacker with write access to a PI Server could trick a user into interacting with a PI Web API endpoint and redirect them to a malicious website. As a result, a victim may disclose sensitive information to the attacker or be provided with false information. Affected products include: Osisoft Pi Web Api.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 4.8 MEDIUM

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

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Privileges Required

High

User Interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

DescriptionNVD

A remote authenticated attacker with write access to a PI Server could trick a user into interacting with a PI Web API endpoint and redirect them to a malicious website. As a result, a victim may disclose sensitive information to the attacker or be provided with false information.

Threat Intelligence Overview

EPSS Score

0.7%

Top 52% 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 MEDIUM

CISA KEV No

Public POC No

EPSS 0.7%

Patch available No

Active threat No

Deciding rule

MEDIUM severity (CVSS 4.0-6.9)

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.