Uncontrolled Recursion Affecting symfony/expression-language package, versions <5.4.54>=6.0.0, <6.4.48>=7.0.0, <7.4.21>=8.0.0, <8.1.9
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-PHP-SYMFONYEXPRESSIONLANGUAGE-21203958
- published18 Oct 2026
- disclosed15 Oct 2026
- creditBruno Dias
Introduced: 15 Oct 2026
NewCVE-2026-109449 (opens in a new tab)How to fix?
Upgrade symfony/expression-language to version 5.4.54, 6.4.48, 7.4.21, 8.1.9 or higher.
Overview
Affected versions of this package are vulnerable to Uncontrolled Recursion via the expression parser in Parser.php, which builds a node tree with no bound on nesting depth. An attacker can supply an expression containing tens of thousands of nested unary operators, array literals, binary operators, or property accesses; the expression parses successfully but the resulting tree causes a segfault on teardown, crashing the process. The fix introduces a maximum nesting level of 256 nodes on any single branch, enforced at both recursive-descent and iterative fold sites (parseExpression, parseConditionalExpression, parsePostfixExpression).