CVE-2026-45133: sensiolabs symfony Uncontrolled Recursion

Vulnerability summary

CVE-2026-45133 is a high (CVSS 8.2) Uncontrolled Recursion vulnerability in sensiolabs symfony. EPSS estimates a 0.63% chance of exploitation in the next 30 days, higher than 49.4% of scored vulnerabilities.

Timeline

1. 14-07-2026
   PublishedVulnerability first disclosed.
2. 15-07-2026
   Last modifiedVulnerability information updated.

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, when the parser is exposed to attacker-controlled input, deeply nested mappings or sequences cause both the block-level (Parser::parseBlock()) and inline (Inline::parseSequence() / Inline::parseMapping()) parsers to recurse without a depth limit. A crafted document exhausts the PHP stack and crashes the worker. This issue is fixed in versions 5.4.52, 6.4.40, 7.4.12, and 8.0.12.

• CWE-674Uncontrolled RecursionThe product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack.
• CWE-776Improper Restriction of Recursive Entity References in DTDs ('XML Entity Expansion')The product uses XML documents and allows their structure to be defined with a Document Type Definition (DTD), but it does not properly control the number of recursive definitions of entities.
• CWE-1333Inefficient Regular Expression ComplexityThe product uses a regular expression with a worst-case computational complexity that is inefficient and possibly exponential.