YAML Parsing Vulnerability in Symfony Framework Exposes Memory Resources
CVE-2026-45304

8.7HIGH

Key Information:

Vendor

Symfony

Status
Symfony
Yaml
Vendor
CVE Published:
14 July 2026

What is CVE-2026-45304?

Symfony, a widely-used PHP framework, has a vulnerability in the YAML component that allows untrusted input to expand into excessively large data structures. This can lead to significant memory exhaustion, impacting the performance and availability of applications utilizing the framework. Versions prior to 5.4.52, 6.4.40, 7.4.12, and 8.0.12 are affected. Users are advised to update to the latest versions to mitigate this risk.

Affected Version(s)

symfony < 5.4.52 < 5.4.52

symfony >= 6.0.0-BETA1, < 6.4.40 < 6.0.0-BETA1, 6.4.40

symfony >= 7.0.0-BETA1, < 7.4.12 < 7.0.0-BETA1, 7.4.12

References

https://github.com/symfony/symfony/security/advisories/GH...
x_refsource_CONFIRM
https://github.com/symfony/symfony/commit/e77391b2e4f1882...
x_refsource_MISC
https://github.com/symfony/symfony/releases/tag/v5.4.52
x_refsource_MISC

CVSS V4

Score:
8.7
Severity:
HIGH
Confidentiality:
None
Integrity:
None
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.