Atomicorp WAF Research Note: CVE-2026-11423

Path Traversal in Altium Enterprise Server Collaboration Service Allows Privilege Escalation

CVE Details

• Already protected by existing Atomicorp WAF rules
• Protection status: Understanding Atomicorp WAF Protection Status
• CVE: CVE-2026-11423
• Name: Path Traversal in Altium Enterprise Server Collaboration Service Allows Privilege Escalation
• Severity: Critical
• CVSS: 9.4 (v4.0) (Critical)
• CVSS version: 4.0
• CVSS source: Altium CNA
• CVSS vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
  • Attack vector: Network
  • Attack complexity: Low
  • Attack requirements: None
  • Privileges required: Low
  • User interaction: None
  • Vulnerable-system confidentiality: High
  • Vulnerable-system integrity: High
  • Vulnerable-system availability: High
  • Subsequent-system confidentiality: High
  • Subsequent-system integrity: High
  • Subsequent-system availability: High
  • Scope: X
• CWE: CWE-22 — Improper Limitation of a Pathname to a Restricted Directory (‘Path Traversal’), CWE-269 — Improper Privilege Management
• Related CAPEC attack patterns (via MITRE CWE relationships): CAPEC-122 (opens in a new tab) , CAPEC-126 (opens in a new tab) , CAPEC-233 (opens in a new tab) , CAPEC-58 (opens in a new tab) , CAPEC-64 (opens in a new tab) , CAPEC-76 (opens in a new tab) , CAPEC-78 (opens in a new tab) , CAPEC-79 (opens in a new tab)
• Vendor: Altium
• Vulnerable product: Altium Enterprise Server
• CVE published: 2026-06-05
• CVE last modified: 2026-07-23
• EPSS: 0.0032; 24.9th percentile (FIRST (opens in a new tab) )
• Latest Update: 2026-09-06
• Selected Rule IDs observed: 344360 , 390709
• Matching rules: 2; rules with blocking actions: 2
• Would-block Rule IDs: 344360 , 390709
• Request surfaces inspected: JSON request data, Request argument names, Request arguments, Request cookies, Request filename, SOAP request data, XML request data

Vulnerability Description

A path traversal vulnerability exists in the Altium Enterprise Server Collaboration Service due to improper handling of user-supplied filenames in the MCAD and Simulation file download flows. A regular authenticated user can submit a collaboration message containing a crafted filename, which is later used to construct the download path on the server without validation, allowing arbitrary files to be read from the server filesystem.

Because the readable files include the server’s master configuration, which stores credentials for privileged accounts, exploitation can lead to authenticating as a system administrator and gaining full control of the server. Altium 365 cloud deployments are not affected.

Recommended Actions

1. Maintain the observed Atomicorp protections. Keep your Atomicorp commercial rules current and confirm that the selected observed rules (344360 , 390709 ) have not been locally disabled. Atomicorp commercial rules are enabled by default. If you use Atomic WAF, review the applicable policy and rule settings.

2. Apply the vendor’s remediation. WAF protection is defense in depth and does not replace upgrading or following the affected vendor’s guidance.

   • Affected versions: Altium Altium Enterprise Server versions earlier than 8.1.1.
   • Recommended upgrade: Upgrade Altium Altium Enterprise Server to 8.1.1 or later.

3. Validate after changes. Confirm rule updates are current, review WAF events for the affected application, and test application behavior after vendor upgrades, mitigations, or local policy changes.

Research Notes

Atomicorp WAF protections are designed around attack techniques and exploit behaviors, allowing existing protections to apply across multiple vulnerabilities without requiring a unique rule for every CVE.

Public Vulnerability References

• NVD (opens in a new tab)
• CVE Record (opens in a new tab)
• CVE authority reference: https://www.altium.com/platform/security-compliance/security-advisories (opens in a new tab)

Test or Research Source

• Source: Atomicorp AI Research Framework
• Tags: cve, derived, traversal, waf-probe

Research Note Context

This research note documents exploit-technique analysis associated with this vulnerability and references Atomicorp WAF protections observed during engineering review, testing, or validation activities.

Atomicorp security controls are generally designed to identify and mitigate attack techniques and exploit behaviors rather than individual CVE identifiers. As a result, protections developed for one vulnerability may also apply to related attack variants and future vulnerabilities using similar techniques.

Learn More

Atomicorp develops commercially supported security technologies for web applications, servers, endpoints, workloads, and legacy enterprise platforms.

Organizations interested in protecting systems against exploit techniques associated with vulnerabilities such as this one can learn more about:

• Atomic ModSecurity Rules: commercially maintained WAF rules for ModSecurity deployments, including protections for web attacks, bots, scanners, malware, exploitation attempts, and emerging vulnerability classes.
• Atomic WAF: an enterprise web application firewall with Atomicorp rules, centralized management, reporting, authentication controls, and operational tooling.
• Atomic ModSecurity Integrator: a special licensing option for MSPs, MSSPs, OEMs, VARs, reverse proxy providers, and other integrators who want to incorporate Atomicorp ModSecurity rule technology into their own products or services.
• Atomic OSSEC: an enterprise OSSEC-based intrusion detection, compliance, and security monitoring platform.
• Atomic Protector: workload protection for Linux, web, cloud, data center, and hybrid environments.

For additional information, product evaluations, or technical discussions, visit https://www.atomicorp.com/ or https://modsecurity.io/ (opens in a new tab) .