Ghostwire

CVE-2026-45304: Symfony's YAML Parser Vulnerable to Exponential Memory Allocation via Recursive Collection-Alias Expansion ("Billion...

LOW CVSS 2.5 Exploit Available

Published: May 27, 2026 | Last Modified: May 27, 2026

Description

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

Ghostwire Analysis — What This Means Practically

Exploit code is reported to be available, increasing the likelihood of active exploitation.

This analysis is generated by Ghostwire from NVD, CISA KEV, EPSS, and open-source intelligence data. Verify findings through primary sources before acting.

References

github.com/symfony/symfony/security/advisories/GHSA-4qpc-3hr4-r2p4
github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573674c8ed4a970a
github.com/FriendsOfPHP/security-advisories/blob/master/symfony/symfony/CVE-2026
github.com/FriendsOfPHP/security-advisories/blob/master/symfony/yaml/CVE-2026-45
symfony.com/cve-2026-45304
github.com/advisories/GHSA-4qpc-3hr4-r2p4
www.tenable.com/cve/CVE-2026-45304
www.cnnvd.org.cn/home/globalSearch?keyword=CVE-2026-45304