Symfony: Unbounded Nesting in the Expression Parser Lets Untrusted Expressions Crash the Process

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-109449
StatePUBLISHED
AssignerCheckmarx
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-15 16:17:43 UTC
Updated2026-10-16 16:00:33 UTC
DescriptionIn 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.

Risk And Classification

Primary CVSS: v4.0 8.7 HIGH from 596c5446-0ce5-4ba2-aa66-48b3b757a647

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Problem Types: CWE-674 | CWE-674 CWE-674 Uncontrolled Recursion

VersionSourceTypeScoreSeverityVector
4.0596c5446-0ce5-4ba2-aa66-48b3b757a647Secondary8.7HIGHCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/C...
4.0CNACVSS8.7HIGHCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CVSS v4.0 Breakdown

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
None
User Interaction
None
Confidentiality
None
Integrity
None
Availability
High
Sub Conf.
None
Sub Integrity
None
Sub Availability
None

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Sensiolabs Symfony affected v5.4.54 git Not specified
CNA Sensiolabs Symfony affected v6.0.0-BETA1 v6.4.48 git Not specified
CNA Sensiolabs Symfony affected v7.0.0-BETA1 v7.4.21 git Not specified
CNA Sensiolabs Symfony affected v8.0.0-BETA1 v8.1.9 git Not specified

References

ReferenceSourceLinkTags
github.com/symfony/symfony/pull/66723 596c5446-0ce5-4ba2-aa66-48b3b757a647 github.com
github.com/symfony/symfony/security/advisories/GHSA-7rpj-w9pf-39rr 596c5446-0ce5-4ba2-aa66-48b3b757a647 github.com
github.com/symfony/symfony/pull/66720 596c5446-0ce5-4ba2-aa66-48b3b757a647 github.com
github.com/symfony/symfony/pull/65690 596c5446-0ce5-4ba2-aa66-48b3b757a647 github.com
symfony.com/blog/cve-2026-109449-unbounded-nesting-in-the-expression-pars... 596c5446-0ce5-4ba2-aa66-48b3b757a647 symfony.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Nicolas Grekas (en)

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