CVE-2026-45133

Symfony: [Yaml] Harden the parser when handling untrusted input

State: Published
Severity: 8.2 High
Published: Jul 14, 2026
Updated: Jul 15, 2026
Reserved: May 8, 2026

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.

Scores

CVSS	Score	Vector	Source
4.0	8.2 High	CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N	GitHub_M

Weaknesses

CWE-674 Uncontrolled Recursion
CWE-776 Improper Restriction of Recursive Entity References in DTDs ('XML Entity Expansion')
CWE-1333 Inefficient Regular Expression Complexity

Affected Products

Product	Versions
symfonysymfony	< 5.4.52Affected >= 6.0.0-BETA1, < 6.4.40Affected >= 7.0.0-BETA1, < 7.4.12Affected >= 8.0.0-BETA1, < 8.0.12Affected

References

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