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

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.

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N

Attack vector

Network

Complexity

Low

Privileges

None

User interaction

None

Confidentiality

High

Integrity

None

Availability

None

Scope

Changed

Exploitation

Is it being used?

Exploit prediction (EPSS)0.6% · higher than 47% of CVEs

Exploited in the wildNo evidence yet

CISA KEVNot listed

Ransomware campaign useNot known

Affected products

Which versions

HT

http-client · symfony

>= 5.4.0, < 5.4.53 · source: vendor

HT

http-foundation · symfony

>= 6.0.0-BETA1, < 6.4.41; >= 7.0.0-BETA1, < 7.4.13; >= 8.0.0-BETA1, < 8.0.13 · source: vendor

SY

symfony · symfony

>= 5.4.0, < 5.4.53; >= 6.0.0-BETA1, < 6.4.41; >= 7.0.0-BETA1, < 7.4.13; >= 8.0.0-BETA1, < 8.0.13 · source: vendor, NVD