CVE-2026-45304: Sensiolabs Symfony

High severity, CVSS 7.5. EPSS: 0.7% 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. Prior to 5.4.52, 6.4.40, 7.4.12, and 8.0.12, Symfony\Component\Yaml\Parser resolved YAML collection aliases recursively, allowing a small untrusted YAML input to expand into a multi-gigabyte structure and exhaust memory. This issue is fixed in versions 5.4.52, 6.4.40, 7.4.12, and 8.0.12.

Affected products

• Sensiolabs Symfony: before 5.4.52 (fixed in 5.4.52); from 6.0.0, before 6.4.40 (fixed in 6.4.40); from 7.0.0, before 7.4.12 (fixed in 7.4.12); from 8.0.0, before 8.0.12 (fixed in 8.0.12)

Published 2026-07-14. Last modified 2026-07-15.