CVE-2026-48736: Sensiolabs Symfony

High severity, CVSS 8.6. EPSS: 0.6% chance of exploitation in the next 30 days.

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.

Affected products

• Sensiolabs Symfony: from 5.4.0, before 5.4.43 (fixed in 5.4.43); from 6.4.0, before 6.4.41 (fixed in 6.4.41); from 7.0.0, before 7.4.13 (fixed in 7.4.13); from 8.0.0, before 8.0.13 (fixed in 8.0.13)

Published 2026-07-14. Last modified 2026-07-16.