---
id: CVE-2026-123125
title: >-
  Symfony: Ip Constraint public/private Modes Accept IPv4-Mapped and
  IPv4-Compatible IPv6 Addresses allowing SSRF Filter Bypass
summary: "The Symfony Validator component\_IpValidator\_incompletely classifies internal addresses in the filtered modes of the\_Ip\_constraint, so some internal addresses are accepted as public, which can lead to Server-Side Request Forgery (SSRF) in…"
severity: medium
cvss: 6.3
cvssVector: 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N'
cvssSource: cna
cwe:
  - CWE-184
  - CWE-918
vendor: sensiolabs
product: symfony/validator
affected:
  - symfony/validator < 5.4.56
  - symfony/validator >= 6.0.0 < 6.4.50
  - symfony/validator >= 7.0.0 < 7.4.23
  - symfony/validator >= 8.0.0 < 8.1.11
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-11-05T16:58:59.042475Z'
published: '2026-11-05'
updated: '2026-11-05'
sourceUpdated: '2026-11-05T17:00:21.546Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-123125'
references:
  - url: 'https://github.com/symfony/symfony/security/advisories/GHSA-4qpf-57w4-m3wc'
  - url: >-
      https://github.com/symfony/symfony/commit/3bf8ea37fcb402c5ecc502a3f63012df85a7572e
tags:
  - cve.org
ingestedAt: '2026-11-05T22:38:31.415Z'
---

## Overview

The Symfony Validator component IpValidator incompletely classifies internal addresses in the filtered modes of the Ip constraint, so some internal addresses are accepted as public, which can lead to Server-Side Request Forgery (SSRF) 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.

In these modes, IpValidator relies on the PHP flags FILTER_FLAG_NO_PRIV_RANGE and FILTER_FLAG_NO_RES_RANGE to classify addresses as public, private, or reserved. These flags do not cover shared address space (100.64.0.0/10) or IPv4-mapped, IPv4-compatible, and 6to4 IPv6 addresses, which can embed internal IPv4 addresses. A value such as ::ffff:127.0.0.1 can therefore pass validation even though it points to an internal host.
Applications that rely on the Ip constraint to reject internal addresses, for example before making a server-side request to a user-supplied address, can be exposed to SSRF.

## Affected

- `symfony/validator < 5.4.56`
- `symfony/validator >= 6.0.0 < 6.4.50`
- `symfony/validator >= 7.0.0 < 7.4.23`
- `symfony/validator >= 8.0.0 < 8.1.11`

## Remediation

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