CVE-2026-109449
highpriority · track · 0EPSS 0.004 · 32 %ileFREPSS · scored 2026-10-27
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
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 6.6–8.7
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
affected products
Products and version ranges known to be affected.
No affected products recorded.
advisories (1)
Vendor and ecosystem advisories describing this.
- CERTFR-2026-AVI-1324Multiples vulnérabilités dans les produits SymfonyFrançais2026-10-15vendor · certfrFR
sources
Which sources assert this record, and when.
references (5) nvd
External citations — patches, advisories, analysis.
- https://github.com/symfony/symfony/pull/65690
- https://github.com/symfony/symfony/pull/66720
- https://github.com/symfony/symfony/pull/66723
- https://github.com/symfony/symfony/security/advisories/GHSA-7rpj-w9pf-39rr
- https://symfony.com/blog/cve-2026-109449-unbounded-nesting-in-the-expression-parser-lets-untrusted-expressions-crash-the-process
Attackers weaponise vulnerabilities like this against internet-exposed services. See what is exposed on your perimeter with a free passive scan.
Free scan