---
id: "CVE-2026-123119"
kind: "vulnerability"
aliases: ["CVE-2026-123119"]
title: "Symfony HttpClient: DNS rebinding bypasses private network checks, exposing internal hosts"
severity: "low"
cvss: 2.3
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["http-client", "package", "php", "symfony"]
not_affected_if: ["does-not-use-no-private-network-client", "fixed-urls-only"]
published_at: "2026-11-05T13:17:07+00:00"
first_seen_at: "2026-11-05T13:39:09+00:00"
updated_at: "2026-11-05T13:40:05+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-123119", "first_seen_at": "2026-11-05T13:39:09+00:00"}]
exploit_sources: []
---

# Symfony HttpClient: DNS rebinding bypasses private network checks, exposing internal hosts

Symfony's NoPrivateNetworkHttpClient caches the checked IP per host but only pins it on the first request, so later requests resolve DNS again. An attacker who controls a DNS record can switch it to a private IP and use the application to enumerate internal hosts and open ports.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the installed `symfony/http-client` version with `composer show symfony/http-client`
- Look for uses of `NoPrivateNetworkHttpClient` in the codebase, especially where user-supplied URLs are fetched repeatedly through the same client

## Fix

- Symfony `5.4.56`, `6.4.50`, `7.4.23`, and `8.1.11` or later (fixed versions prior to which the component is affected)

## Timeline

- 2026-11-05T13:39:09+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-123119

## Documents

- [advisory] Vendor advisory: github.com https://github.com/symfony/symfony/security/advisories/GHSA-c7hm-wqwp-f9v8
- [fix] Patch: github.com https://github.com/symfony/symfony/commit/ab084826b2b5db8d0b91af635fe2b5e1c4f699f9

## From the sources

The Symfony HttpClient component NoPrivateNetworkHttpClient does not pin the checked IP address of cached hosts, allowing for DNS rebinding to bypass private network restrictions, resulting in enumeration of internal hosts and ports in Symfony versions prior to 5.4.56, 6.x prior to 6.4.50, 7.x prior to 7.4.23, and 8.x prior to 8.1.11.

NoPrivateNetworkHttpClient resolves the host of each request and checks the IP before connecting. It caches the result per host, and passes the IP to the decorated client through the resolve option so that the client connects to the exact IP that was checked. The issue is that resolve was only passed on the first lookup of a host: on subsequent requests, the decorated client resolved the host again on its own.

An attacker who controls a host's DNS can exploit this with DNS rebinding by answering the first lookup with a public IP, and subsequent lookups with a private IP, so when an application sends several requests to that host through the same client, the later requests connect to the private IP. This happens, for example, when an application fetches several URLs of a repository provided by a user. The check of the primary_ip in the on_progress callback still aborts the request before anything is sent, but the connection is made, and the error differs depending on whether the port is open or closed. This allows enumerating internal hosts and ports, as in CVE-2024-50342.

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