CVE-2026-45304

HIGH

Symfony: YAML Parser Exponential Memory Allocation via Recursive Collection-Alias Expansion ("Billion Laughs")

Title source: cna
STIX 2.1

Description

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.

References (6)

Core 6

Scores

CVSS v3 7.5
EPSS 0.0080
EPSS Percentile 53.1%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CISA SSVC

Vulnrichment
Exploitation none
Automatable yes
Technical Impact partial

Details

CWE
CWE-776
Status published
Products (9)
sensiolabs/symfony < 5.4.52
symfony/symfony < 5.4.52
symfony/symfony >= 6.0.0-BETA1, < 6.4.40
symfony/symfony >= 7.0.0-BETA1, < 7.4.12
symfony/symfony >= 8.0.0-BETA1, < 8.0.12
symfony/yaml < 5.4.52
symfony/yaml >= 6.0.0-BETA1, < 6.4.40
symfony/yaml >= 7.0.0-BETA1, < 7.4.12
symfony/yaml >= 8.0.0-BETA1, < 8.0.12
Published Jul 14, 2026
Tracked Since Jul 15, 2026