Vulnerability · Published Jan 15, 2026 · Assigned by Altium
CVE-2026-1009Stored Cross-Site Scripting in Altium Live Forum Leading to Cross-Customer Data Exposure
Critical 9.0
In plain English
A critical-severity cross-site scripting in Altium Live from Altium. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 15% of all known vulnerabilities).
Official description
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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Altium | Altium Live | 0 – through 1.2.2 |
Weakness: CWE-79, CWE-284 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H