Feast Feature Server Path Traversal Vulnerability

Executive Summary

CVE-2026-23537 is a vulnerability in the Feast Feature Server's /save-document endpoint that allows an unauthenticated remote attacker to write arbitrary JSON files to the server's filesystem.

Although the system tries to restrict where files can be written, these protections can be bypassed, enabling attackers to overwrite important application configurations or startup scripts.

This flaw requires no credentials or special privileges, so any attacker with network access to the server can exploit it.

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Impact Analysis

This vulnerability can impact you by allowing unauthorized modifications to the system, such as overwriting vital application configurations or startup scripts.

It can also lead to denial of service through disk exhaustion or potentially enable remote code execution, compromising the integrity and availability of the system.

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Detection Guidance

This vulnerability involves an unauthenticated arbitrary file write via the Feast Feature Server's /save-document endpoint. Detection can focus on monitoring network traffic for suspicious POST requests to this endpoint.

• Use network monitoring tools (e.g., tcpdump or Wireshark) to capture HTTP POST requests targeting the /save-document endpoint.
• Example tcpdump command to capture traffic to port 80 or 443 (adjust port as needed): tcpdump -i any -A 'tcp port 80 and (((ip[2:2] - ((ip[0]&0xf)<<2)) - ((tcp[12]&0xf0)>>2)) != 0)' | grep '/save-document'
• Check server logs for unexpected or unauthorized JSON file writes or POST requests to /save-document.

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Mitigation Strategies

Immediate mitigation steps include restricting network access to the Feast Feature Server, especially to the /save-document endpoint, to trusted users only.

• Apply any available patches or updates from the vendor addressing this vulnerability.
• Implement firewall rules or access controls to block unauthenticated access to the /save-document endpoint.
• Monitor system and application logs for signs of exploitation attempts.

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Compliance Impact

The vulnerability allows unauthenticated remote attackers to write arbitrary JSON files to the server's filesystem, potentially leading to unauthorized system modifications, denial of service, or remote code execution.

Such unauthorized modifications and potential system compromise could impact the integrity and availability of systems that handle sensitive data, which are key requirements under common standards and regulations like GDPR and HIPAA.

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