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.

Attack Vector Network

Attack Complexity Low

Privileges Required None

Attack Requirements None

User Interaction None

Vulnerable System Confidentiality Impact None

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact High

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

No CVSS v3.1

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Exploitation none

Automatable yes

Technical Impact partial

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
symfony symfony affected
Version Status Constraints
< 5.4.52 affected —
>= 6.0.0-BETA1, < 6.4.40 affected —
>= 7.0.0-BETA1, < 7.4.12 affected —
>= 8.0.0-BETA1, < 8.0.12 affected —
symfony yaml affected
Version Status Constraints
< 5.4.52 affected —
>= 6.0.0-BETA1, < 6.4.40 affected —
>= 7.0.0-BETA1, < 7.4.12 affected —
>= 8.0.0-BETA1, < 8.0.12 affected —

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Project Subscriptions

No data.

Advisories
Source ID Title
Debian DSA Debian DSA DSA-6312-1 symfony security update
Debian DSA Debian DSA DSA-6317-1 symfony security update
Github GHSA Github GHSA GHSA-4qpc-3hr4-r2p4 Symfony's YAML Parser Vulnerable to Exponential Memory Allocation via Recursive Collection-Alias Expansion ("Billion Laughs")
Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573674c8ed4a970a cve-icon
https://github.com/symfony/symfony/releases/tag/v5.4.52 cve-icon
https://github.com/symfony/symfony/releases/tag/v6.4.40 cve-icon
https://github.com/symfony/symfony/releases/tag/v7.4.12 cve-icon
https://github.com/symfony/symfony/releases/tag/v8.0.12 cve-icon
https://github.com/symfony/symfony/security/advisories/GHSA-4qpc-3hr4-r2p4 cve-icon
History

Tue, 14 Jul 2026 20:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Tue, 14 Jul 2026 19:00:00 +0000

Type Values Removed Values Added
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.
Title Symfony: YAML Parser Exponential Memory Allocation via Recursive Collection-Alias Expansion ("Billion Laughs")
Weaknesses CWE-776
References
Metrics cvssV4_0

{'score': 8.7, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-07-14T19:13:39.323Z

Reserved: 2026-05-11T20:14:43.202Z

Link: CVE-2026-45304

cve-icon Vulnrichment

Updated: 2026-07-14T19:13:34.393Z

cve-icon NVD

No data.

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses