CVE-2026-48736 Symfony: IpUtils::PRIVATE_SUBNETS Omits IPv6 Transition Forms (6to4, NAT64, Teredo, IPv4-compatible): SSRF Bypass in NoPrivateNetworkHttpClient
Attackers can bypass private network restrictions in Symfony's HTTP client using IPv6 transition forms to access internal resources.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-48736?
CVE-2026-48736 is a medium-severity server-side request forgery vulnerability in Sensiolabs Symfony, published on 14 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Which versions are affected by CVE-2026-48736?
16 open source packages ship an affected version, including symfony/symfony, symfony/http-client and symfony/http-foundation. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
symfony/symfony Packagist | From 5.4.0 | 5.4.53 |
symfony/symfony Packagist | From 5.4.0 | 5.4.53 |
symfony/symfony Packagist | From 6.4.0 | 6.4.41 |
symfony/symfony Packagist | From 6.4.0 | 6.4.41 |
symfony/symfony Packagist | From 7.0.0 | 7.4.13 |
symfony/symfony Packagist | From 7.0.0 | 7.4.13 |
10 more packages
symfony/symfony Packagist | From 8.0.0 | 8.0.13 |
symfony/symfony Packagist | From 8.0.0 | 8.0.13 |
symfony/http-client Packagist | From 5.4.0 | 5.4.53 |
symfony/http-client Packagist | From 5.4.0 | 5.4.53 |
symfony/http-foundation Packagist | From 6.4.0 | 6.4.41 |
symfony/http-foundation Packagist | From 6.4.0 | 6.4.41 |
symfony/http-foundation Packagist | From 7.0.0 | 7.4.13 |
symfony/http-foundation Packagist | From 7.0.0 | 7.4.13 |
symfony/http-foundation Packagist | From 8.0.0 | 8.0.13 |
symfony/http-foundation Packagist | From 8.0.0 | 8.0.13 |
Products include Sensiolabs Symfony.
How do I fix CVE-2026-48736?
Upgrade symfony/symfony to a fixed version for your release line: 5.4.53, 6.4.41, 7.4.13 or 8.0.13.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-48736 being exploited?
There is no known exploitation of CVE-2026-48736 in the wild and no public exploit code.
Other vulnerabilities in Sensiolabs Symfony
Sources
Also known as DEBIAN-CVE-2026-48736, GHSA-38cx-cq6f-5755, UBUNTU-CVE-2026-48736.