CVE-2026-9102Network attack vector

Authenticated arbitrary file writes via traversal filenames

Published May 20, 2026 · Updated May 20, 2026

Path traversal in Altium On-Prem Enterprise Server before 8.0.4 allows remote authenticated users to write arbitrary server files. The ComparisonService Gerber upload APIs use the multipart Content-Disposition filename without sanitizing it before constructing the temporary upload path. A regular workspace account can escape that directory and place controlled content in web-accessible paths for code execution as the service account, or overwrite binaries and configuration to interrupt service.

CVSS severity9.4
Critical
EPSS probability0.56%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Path traversal in Altium On-Prem Enterprise Server before 8.0.4 allows remote authenticated users to write arbitrary server files. The ComparisonService Gerber upload APIs use the multipart Content-Disposition filename without sanitizing it before constructing the temporary upload path. A regular workspace account can escape that directory and place controlled content in web-accessible paths for code execution as the service account, or overwrite binaries and configuration to interrupt service.

The record

CVE
CVE-2026-9102
Published
May 20, 2026
Updated
May 20, 2026
Vendor
Altium
Product
Altium On-Prem Enterprise Server
Classifications
CWE-434, CWE-22, T1505.003
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. May 20, 2026CVE publishedPublication date reported by the CVE source.
  2. May 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <8.0.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Altium · Altium On-Prem Enterprise Serverversion=0 <8.0.4

Published CVSS scores

9.4AltiumCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-434Unrestricted Upload of File with Dangerous Type
CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
T1505.003Server Software Component: Web Shell

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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