CVE Catalog

CVE-2026-109449

HighCVSS 8.7
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.52%

43th percentile - higher than 43% of all known CVEs

Summary

In Symfony Expression Language versions prior to 5.4.54, 6.4.48, 7.4.21, and 8.1.9, the parser built its node tree with no bound on its depth. An expression made of tens of thousands of nested unary operators, array literals, binary operators or property accesses crashed the PHP process while the tree was being freed.

Risk Assessment

An application validating user-written expressions (e.g. via #[Assert\ExpressionSyntax] calling ExpressionLanguage::lint()) can be crashed by a single request, posing a denial-of-service risk. Any code parsing untrusted expressions is similarly affected.

Recommendation

Update symfony/expression-language to version 5.4.54, 6.4.48, 7.4.21, or 8.1.9 (or later). Avoid parsing untrusted expressions without resource limits.

Related vulnerabilities

Original NVD description (English source)

In Symfony Expression Language versions prior to 5.4.54, 6.4.48, 7.4.21, and 8.1.9, the parser of the ExpressionLanguage component built its node tree with no bound on its depth. An expression made of tens of thousands of nested unary operators, array literals, binary operators or property accesses crashed the PHP process, while the tree was being freed. #[Assert\ExpressionSyntax] passes the validated value to ExpressionLanguage::lint(), so an application validating expressions written by its users could be crashed by a single request, and so could any code parsing untrusted expressions. This issue affects symfony/expression-language through v5.4.53, v6.0.0-BETA1 through v6.4.47, v7.0.0-BETA1 through v7.4.20, and v8.0.0-BETA1 through v8.1.8.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS