---
id: CVE-2026-109449
title: "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"
summary: "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 op…"
severity: high
cvss: 8.7
cvssVector: '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'
cwe:
  - CWE-674
vendor: sensiolabs
product: symfony/expression-language
affected:
  - symfony/expression-language < v5.4.54
  - symfony/expression-language >= v6.0.0-BETA1 < v6.4.48
  - symfony/expression-language >= v7.0.0-BETA1 < v7.4.21
  - symfony/expression-language >= v8.0.0-BETA1 < v8.1.9
published: '2026-10-15'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T19:17:21.243'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-109449'
references:
  - url: 'https://github.com/symfony/symfony/pull/65690'
    label: 596c5446-0ce5-4ba2-aa66-48b3b757a647
  - url: 'https://github.com/symfony/symfony/pull/66720'
    label: 596c5446-0ce5-4ba2-aa66-48b3b757a647
  - url: 'https://github.com/symfony/symfony/pull/66723'
    label: 596c5446-0ce5-4ba2-aa66-48b3b757a647
  - url: 'https://github.com/symfony/symfony/security/advisories/GHSA-7rpj-w9pf-39rr'
    label: 596c5446-0ce5-4ba2-aa66-48b3b757a647
  - url: >-
      https://symfony.com/blog/cve-2026-109449-unbounded-nesting-in-the-expression-parser-lets-untrusted-expressions-crash-the-process
    label: 596c5446-0ce5-4ba2-aa66-48b3b757a647
tags:
  - nvd
  - cve.org
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-10-15T18:05:16.968511Z'
cvssSource: cna
ingestedAt: '2026-10-15T16:13:11.186Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.