---
id: CVE-2026-78205
title: >-
  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)
summary: >-
  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 …
severity: medium
cvss: 5.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N'
cwe:
  - CWE-918
published: '2026-08-24'
updated: '2026-09-24'
sourceUpdated: '2026-09-24T20:44:42.207'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-78205'
references:
  - url: 'https://github.com/bentoml/BentoML'
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/bentoml/BentoML/blob/v1.4.39/src/bentoml/_internal/utils/uri.py#L89-L96
    label: disclosure@vulncheck.com
  - url: 'https://github.com/bentoml/BentoML/issues/5644'
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/bentoml-through-server-side-request-forgery-via-unfiltered-rfc-6598-shared-address-space
    label: disclosure@vulncheck.com
tags:
  - nvd
epss: 0.0041
epssPercentile: 0.32416
ingestedAt: '2026-09-24T20:51:40.218Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.