CVE-2026-11420: Altium On-prem Enterprise Server remote code execution (CVSS 9.8)

Description

Two path traversal vulnerabilities in the Network Installation Service (NIS) of Altium Enterprise Server allow an unauthenticated network attacker to write arbitrary files to any writable location on the server filesystem and to read package archive files from the server. No authentication, session, or credentials are required. Because content-controlled files can be written to web-accessible directories, or used to overwrite application binaries or configuration files, exploitation can be escalated to remote code execution in the context of the service account, and can disclose deployment package contents. Altium 365 cloud deployments are not affected, as the Network Installation Service is not part of the cloud offering.

CVSS 3.1 breakdown

Attack vectorNetwork

Attack complexityLow

Privileges requiredNone

User interactionNone

ScopeUnchanged

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

Altium On-prem Enterprise Server< 8.1.1

Remediation

Fixed in

Altium On-prem Enterprise Server≥ 8.1.1

Patch & vendor advisories

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

References

https://www.altium.com/platform/security-compliance/security-advisoriesVendor Advisory

Related CVEs

Recent high-severity vulnerabilities sharing a weakness type.

Frequently asked

Is CVE-2026-11420 being actively exploited?

CVE-2026-11420 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.71%.

How severe is CVE-2026-11420?

CVE-2026-11420 has a CVSS 3.1 base score of 9.8, rated critical. EPSS estimates a 0.71% probability of exploitation.

Which products are affected by CVE-2026-11420?

Affected products include Altium On-prem Enterprise Server.

How do I fix CVE-2026-11420?

Upgrade affected software to a fixed version, for example Altium On-prem Enterprise Server 8.1.1 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-11420 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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