Stored Cross-Site Scripting in Altium Live Support Center Comment Endpoint

published 2026-01-15 9 mo ago modified 2026-06-17 4 mo ago also EUVD-2026-2999

cvss: 6.1; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.3%; EPSS 0.3% chance of exploitation in 30 days, percentile 21%
public exploits: 0; none known

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.

Patch / fix

fixed in 1

Altium Altium Live 1.1.1.40

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 9 mo ago (2026-01-16)

Exploit prediction

0.29% chance of exploitation in the next 30 days, higher than 21% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	6.1	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Affected products

Altium Altium Live

Classification

Weakness

CWE-79 Improper Neutralization of Input During Web Page Generation
CWE-116 Improper Encoding or Escaping of Output

References

altium.com /platform/security-compliance/security-advisories
vendor-advisory

Sources

CVE List CVE-2026-1011
NVD CVE-2026-1011

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary