CVE-2026-78205
Received Received - Intake

BentoML Outbound SSRF via CGNAT IP Bypass

Publication date: 2026-08-24

Last updated on: 2026-08-24

Assigner: VulnCheck

Description
BentoML's outbound connection safeguard (make_safe_connect in _internal/utils/uri.py) blocks private, loopback, and link-local IP addresses but fails to reject the RFC 6598 shared address space (100.64.0.0/10, CGNAT). In versions 1.4.19 through 1.4.39, an unauthenticated attacker can supply URLs pointing to that range via multipart file handling (MultipartSerde.ensure_file) or JSON request parsing (JSONSerde.parse_request), causing the server to make outbound requests to internal hosts on CGNAT networks (Server-Side Request Forgery). This is an incomplete fix for CVE-2025-54381.

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Meta Information

Published
2026-08-24
Last Modified
2026-08-24
Generated
2026-08-24
AI Q&A
2026-08-24
EPSS Evaluated
N/A
NVD
CVE-2026-78205
EUVD
EUVD-2026-64680

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
bentoml bentoml From 1.4.19 (inc) to 1.4.39 (inc)
bentoml bentoml to 1.4.39 (inc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-918 The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.

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Executive Summary

This is a Server-Side Request Forgery (SSRF) vulnerability in BentoML where the outbound connection safeguard fails to block RFC 6598 shared address space (100.64.0.0/10, CGNAT). An unauthenticated attacker can exploit this by supplying URLs pointing to this range via file handling or JSON parsing, causing the server to make unintended outbound requests to internal hosts on CGNAT networks.

Detection Guidance

To detect this vulnerability, monitor outbound HTTP requests from your BentoML server to the RFC 6598 CGNAT range (100.64.0.0/10). Check server logs for requests to addresses like 100.64.1.1. Use network monitoring tools to inspect traffic from BentoML processes.

Impact Analysis

An attacker could exploit this to probe or access internal services within your network, potentially leading to data breaches, unauthorized access, or further network compromise. The impact is higher in cloud environments where CGNAT IPs are used for internal services.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, violating compliance requirements such as GDPR (data protection) and HIPAA (healthcare data privacy). Exploitation may result in data breaches, triggering regulatory penalties and legal consequences.

Mitigation Strategies

Upgrade BentoML to the latest version beyond 1.4.39 where the fix is applied. Temporarily block outbound traffic to the 100.64.0.0/10 range at your firewall. Review and restrict file upload endpoints to prevent malicious input.

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