How severe is CVE-2026-1009?

CVE-2026-1009 has a CVSS 3.x base score of 9.0, rated critical severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-1009 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (12th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-1009?

CVE-2026-1009 affects Altium Altium Live. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-1009?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

Does CVE-2026-1009 have an EU (EUVD) identifier?

Yes. CVE-2026-1009 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-3041.

When was CVE-2026-1009 published?

CVE-2026-1009 was published on 2026-01-15 and last updated on 2026-06-17.

CVE-2026-1009

CVE-2026-1009 is a critical-severity vulnerability in Altium Altium Live with a CVSS 3.x base score of 9.0. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-79.

Key facts

Severity: Critical (CVSS 3.x base score 9.0)
EPSS exploit prediction: 0% (12th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-3041
Weakness: CWE-79
Affected product: Altium Altium Live
Published: 2026-01-15
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2026-1009?: 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.
How severe is CVE-2026-1009?: CVE-2026-1009 has a CVSS 3.x base score of 9.0, rated critical severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-1009 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (12th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-1009?: CVE-2026-1009 affects Altium Altium Live. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-1009?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2026-1009 have an EU (EUVD) identifier?: Yes. CVE-2026-1009 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-3041.
When was CVE-2026-1009 published?: CVE-2026-1009 was published on 2026-01-15 and last updated on 2026-06-17.

References

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

Affected products (1)

cpe:2.3:a:altium:altium_live:1.2.2:*:*:*:*:*:*:*

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