CVE-2026-11419: Altium Enterprise Server Path Traversal

CVE-2026-11419 Overview

CVE-2026-11419 is a path traversal vulnerability in the Altium Enterprise Server Vault Service UploadController. The flaw stems from improper validation of a user-controlled path component in image upload requests [CWE-22]. An authenticated user can supply a crafted absolute path that bypasses the configured storage root, writing arbitrary files anywhere the service account can write.

Attackers can escalate the file-write primitive to remote code execution, service takeover, or denial of service. Web-accessible directories, application binaries, and configuration files are all viable targets. Altium 365 cloud deployments are not affected because the endpoint is unreachable and the cloud storage architecture neutralizes the write primitive.

Critical Impact

Authenticated attackers can write arbitrary files to the server filesystem, leading to remote code execution and full service takeover.

Affected Products

• Altium Enterprise Server (on-premises) Vault Service
• UploadController image upload endpoint
• Altium 365 cloud deployments are NOT affected

Discovery Timeline

• 2026-06-05 - CVE-2026-11419 published to the National Vulnerability Database (NVD)
• 2026-06-05 - Last updated in NVD database

Technical Details for CVE-2026-11419

Vulnerability Analysis

The Altium Enterprise Server Vault Service exposes an image upload endpoint handled by the UploadController. The controller accepts a path component from authenticated clients and joins it with the service's configured storage root before writing the uploaded content.

The join operation does not normalize or constrain the user-supplied value. When the supplied path is absolute, standard path-joining behavior in many runtimes discards the prior root and uses the attacker-controlled absolute path instead. The upload is then written to that location with the privileges of the service account.

Because the attacker controls both the destination and the file contents, the primitive supports overwriting binaries, dropping web shells into web-accessible directories, or replacing configuration files consumed at startup. Each path leads to remote code execution or service takeover.

Root Cause

The root cause is improper validation of a path component supplied through the upload request [CWE-22]. The controller fails to reject absolute paths, traversal sequences, and paths that resolve outside the configured storage root. No canonicalization or boundary check is performed before the write.

Attack Vector

Exploitation requires authenticated access over the network and low complexity. The attacker sends an image upload request to the Vault Service with a crafted absolute path. The service writes attacker-controlled content to the chosen filesystem location, restricted only by the permissions of the service account.

// No verified public proof-of-concept code is available.
// The vulnerability is triggered by supplying a crafted absolute
// path in the image upload request handled by UploadController,
// causing the configured storage root to be discarded.
// Refer to the Altium Security Advisory for technical details.

Detection Methods for CVE-2026-11419

Indicators of Compromise

• Files written by the Vault Service account outside the configured storage root, especially in web roots, binary directories, or configuration paths
• Image upload requests to the UploadController containing absolute paths, drive letters, or .. traversal sequences
• Unexpected new files in directories such as wwwroot, service install paths, or startup script locations created during a Vault Service session
• Modified timestamps on existing application binaries or configuration files of the Vault Service

Detection Strategies

• Inspect Vault Service HTTP logs for upload requests where the path parameter begins with a drive letter, slash, or contains .. segments
• Baseline the expected storage root and alert on writes by the Vault Service process to any path outside that root
• Correlate authenticated session identifiers with anomalous file creation events on the host
• Review File Integrity Monitoring (FIM) output for changes to Altium binaries, IIS-served content, or configuration files

Monitoring Recommendations

• Enable verbose request logging on the Enterprise Server and forward to a central log store for retention and search
• Monitor process-level file write telemetry from the Vault Service account using endpoint detection telemetry
• Alert on creation of executable, script, or .config files in any directory writable by the service account

How to Mitigate CVE-2026-11419

Immediate Actions Required

• Apply the vendor-supplied update from the Altium Security Advisory as soon as available
• Restrict network access to the Enterprise Server Vault Service to trusted administrative networks only
• Audit accounts with authenticated access and remove unused or shared credentials
• Review the filesystem for unauthorized files written by the Vault Service account since deployment

Patch Information

Altium has published guidance through the Altium Security Advisory. Administrators of on-premises Enterprise Server installations should consult the advisory for fixed version details and upgrade procedures. Altium 365 cloud customers require no action because the endpoint is not reachable in that deployment model.

Workarounds

• Run the Vault Service under a least-privilege account with write access limited strictly to the configured storage root
• Place the Enterprise Server behind a reverse proxy or web application firewall that rejects upload requests containing absolute paths or traversal sequences
• Apply filesystem ACLs that deny the service account write access to web roots, binary directories, and configuration paths
• Disable or block the affected upload endpoint at the network layer until the patch is applied

# Example: restrict the Vault Service account from writing outside its storage root on Linux
# Replace <svc_user> and <storage_root> with deployment-specific values
chown -R <svc_user>:<svc_user> <storage_root>
find / -xdev -writable -user <svc_user> ! -path "<storage_root>/*" -print
# Review the output and remove write permissions where the service account does not require them