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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| sensiolabs | symfony | — | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | symfony | 7.4.21+dfsg-1 | — |
| Debian 13 | symfony | 6.4.49+dfsg-0+deb13u1 | — |
| Debian 12 | symfony | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | symfony | No fix yet | — |
| Ubuntu 26.04 LTS | symfony | No fix yet | — |
| Ubuntu 16.04 LTS | symfony | No fix yet | — |
Show 4 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 24.04 LTS | symfony | No fix yet | — |
| Ubuntu Pro 22.04 LTS | symfony | No fix yet | — |
| Ubuntu Pro 20.04 LTS | symfony | No fix yet | — |
| Ubuntu Pro 18.04 LTS | symfony | No fix yet | — |
References
- https://github.com/symfony/symfony/security/advisories/GHSA-7rpj-w9pf-39rr third-party-advisory
- https://symfony.com/blog/cve-2026-109449-unbounded-nesting-in-the-expression-parser-lets-untrusted-expressions-crash-the-process vendor-advisory
- https://github.com/symfony/symfony/pull/65690 patch
- https://github.com/symfony/symfony/pull/66720 patch
- https://github.com/symfony/symfony/pull/66723 patch