CVE-2026-109449: CWE-674 Uncontrolled Recursion in sensiolabs symfony
Description
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.
CVSS v4.0
Score 8.7high
Affected software
sensiolabs
symfony
pkg:composer/symfony/expression-languageRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The Symfony Expression Language component in affected versions builds its node tree without bounding its depth. Expressions containing tens of thousands of nested unary operators, array literals, binary operators, or property accesses cause uncontrolled recursion during parsing and freeing of the tree, crashing the PHP process. This vulnerability (CWE-674) can be exploited by submitting deeply nested expressions, potentially causing denial of service in applications that parse or validate untrusted expressions using ExpressionLanguage::lint().
Potential Impact
An attacker can cause a denial of service by crashing the PHP process through crafted expressions with excessive nesting depth. This affects applications using the ExpressionLanguage component to parse or validate user-supplied expressions, potentially leading to service disruption.
Mitigation Recommendations
A fix is available in Symfony Expression Language versions 5.4.54, 6.4.48, 7.4.21, and 8.1.9. Users should upgrade to these or later versions to mitigate the vulnerability. No vendor advisory content was provided to indicate alternative mitigations or temporary fixes.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- Checkmarx
- Date Reserved
- 2026-10-12T16:57:32.590Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6ad0f5fd2cdf04f65641fe09
Added to database: 10/15/2026, 15:49:17 UTC
Last enriched: 10/15/2026, 16:04:10 UTC
Last updated: 10/15/2026, 19:00:26 UTC
Views: 9
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