Uncontrolled Recursion in Symfony - CVE-2026-45133
Published: May 21, 2026
Vulnerability identifier: #VU132075
CSH Severity: Medium
CVSS v4.0: 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/E:U/U:Green
CVE-ID: CVE-2026-45133
CWE-ID: CWE-674
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: SensioLabs
Affected software:
Symfony
Symfony
Detailed vulnerability description
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to uncontrolled recursion in Symfony\Component\Yaml\Parser when parsing attacker-controlled YAML input with deeply nested blocks, sequences, or mappings. A remote attacker can supply a specially crafted YAML document to cause a denial of service.
The issue can exhaust the PHP stack and crash the worker.
How to mitigate CVE-2026-45133
Install security update from vendor's website.