What is the CVSS score of CVE-2026-1009?

CVE-2026-1009 has a CVSS 3.1 base score of 9.0 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H. EPSS exploitation probability: 0.0%.

How to fix or mitigate CVE-2026-1009?

Within 24 hours: Identify all affected systems and apply vendor patches immediately. Verify anti-CSRF tokens and content security policies are enforced.

Altium Live CVE-2026-1009

CRITICAL

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

2026-01-15 4760f414-e1ae-4ff1-bdad-c7a9c3538b79

XSS Altium Live Altium

9.0

CVSS 3.1 · NVD

View

Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

Access

Authenticate to Altium Forum
Delivery

Inject malicious JavaScript in forum post
Exploit

Victim views post
Execution

JavaScript executes in victim's session
Impact

Access workspace data and files

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
Exploitation Conditions	Attacker must have valid Altium Forum authentication credentials. Victim user must view the malicious forum post. Forum post content field lacks server-side input sanitization for JavaScript payloads.
Impact	CVSS 9.0 (Critical). Low privileges, user interaction, scope change. EPSS 0.02%.
Exploit ScenarioDerived	An attacker posts a forum message with JavaScript that steals Altium session tokens, enabling access to the victim's PCB design projects and intellectual property.

Act Now Prioritize within 24-48h. Why: CRITICAL severity.

No patch listed yet 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 12, 2026

Altium Forum has stored XSS in forum posts with scope change (CVSS 9.0). Authenticated attackers can inject JavaScript that executes in other users' sessions, including accessing Altium design tools and project data.

Earlier versions of this analysis (1)

v1 Mar 12, 2026 - 21:54 CVSS 9.0

Altium Forum stored XSS enables session hijacking and access to PCB design data.

RemediationAI

Implement server-side HTML sanitization on all forum content. Add CSP headers.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

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

Technical ContextAI · show details

Forum post content is not server-side sanitized (CWE-79). Injected JavaScript executes in authenticated user sessions. Altium users work with proprietary PCB designs and hardware IP.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 9.0 CRITICAL

AV:N/AC:L/PR:L/UI:R/S:C/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

Low

User Interaction

Required

Scope

Changed

Confidentiality

High

Integrity

High

Availability

High

DescriptionCVE.org

A stored cross-site scripting (XSS) vulnerability exists in the Altium Forum due to missing server-side input sanitization in forum post content. An authenticated attacker can inject arbitrary JavaScript into forum posts, which is stored and executed when other users view the affected post. Successful exploitation allows the attacker’s payload to execute in the context of the victim’s authenticated Altium 365 session, enabling unauthorized access to workspace data, including design files and workspace settings. Exploitation requires user interaction to view a malicious forum post.

Executive ViewAI

Why It Matters

CVE-2026-1009 presents critical security risk, a cross-site scripting vulnerability rated CVSS 9.0. Attackers could inject malicious scripts to steal user sessions, credentials, or perform actions on behalf of authenticated users. Organizations should apply vendor updates immediately when available and implement compensating controls in the interim.

Business Impact: Severe

Compensating Controls

Apply vendor patch. If immediate patching is not feasible: (1) Implement Content-Security-Policy headers; (2) Enable HttpOnly and SameSite cookie attributes; (3) Deploy WAF XSS/CSRF rules.

Threat Intelligence Overview

EPSS Score

0.0%

Top 97% exploitable

Data Quality

3 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 CRITICAL

CISA KEV No

Public POC No

EPSS 0.0%

Patch available No

Active threat No

Deciding rule

CRITICAL severity

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.