CVE-2026-1009: A stored cross-site scripting (XSS) vulnerability exists in the Altium Forum due to missing server-side input

This month

CRITICAL 9.0DOWNGRADE

CVE-2026-1009 is a critical-severity flaw (CVSS 9.0) affecting altium live. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

Critical severity

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	9.0 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	Required
EPSS exploit chance	0.2% (top 85%)
CISA exploited list	No
Weakness	CWE-79, CWE-284
Published	2026-01-15
Last modified	2026-06-17

Publisher (CNA): Altium · Vendor: altium

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-01-15 23:15 UTCPublished CVE record published
2026-06-17 10:14 UTCUpdated Record last modified

altium altium live DOWNGRADE

Affected: 1.2.2

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.2.2

1. Check installed version

apt-cache policy altium-live || rpm -q altium-live || altium-live --version

2. No fixed release: DOWNGRADE to a release before 1.2.2 (Debian / Ubuntu)

apt-cache madison altium-live sudo apt install altium-live=<VERSION_BEFORE_1.2.2> sudo apt-mark hold altium-live

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list altium-live sudo dnf downgrade altium-live-<VERSION_BEFORE_1.2.2> sudo dnf versionlock add altium-live

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-1009?

altium live: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-1009 being exploited?

CVE-2026-1009 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-1009 affect?

CVE-2026-1009 affects altium live. Severity is critical (CVSS 9.0). 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 an

How urgent is CVE-2026-1009?

Priority 35/100. Critical severity

Related CVEs

CVE-2026-1011 MEDIUM 6.1 UPGRADE A stored cross-site scripting (XSS) vulnerability exists in the Altium Support Center AddComment endpoint due
CVE-2026-1008 HIGH 7.6 DOWNGRADE A stored cross-site scripting (XSS) vulnerability exists in the user profile text fields of Altium 365

References

← Back to latest CVEs