CVE-2026-1011: Stored Cross-Site Scripting in Altium Live Support Center Comment Endpoint

Severity: medium (CVSS 6.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-01-16 · updated 2026-06-17
Weakness: CWE-79

Description

A stored cross-site scripting (XSS) vulnerability exists in the Altium Support Center AddComment endpoint due to missing server-side input sanitization. Although the client interface applies HTML escaping, the backend accepts and stores arbitrary HTML and JavaScript supplied via modified POST requests. The injected content is rendered verbatim when support cases are viewed by other users, including support staff with elevated privileges, allowing execution of arbitrary JavaScript in the victim’s browser context.

Affected products

Altium Live: through 1.1.1.39

References

https://www.altium.com/platform/security-compliance/security-advisories

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