CVE-2026-45304

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 structur...

GHSA-4QPC-3HR4-R2P4 Symfony's YAML Parser Vulnerable to Exponential Memory Allocation via Recursive Collection-Alias Expansion ("Billion Laughs")

Description Symfony\Component\Yaml\Parser resolves YAML aliases anchor during parsing. Aliases that reference collections arrays, stdClass, TaggedValue-wrapped collections can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small inpu...

Symfony's YAML Parser Vulnerable to Exponential Memory Allocation via Recursive Collection-Alias Expansion ("Billion Laughs")

Description Symfony\Component\Yaml\Parser resolves YAML aliases anchor during parsing. Aliases that reference collections arrays, stdClass, TaggedValue-wrapped collections can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small inpu...