Description
In Symfony YAML prior to versions 5.4.54, 6.4.45, 7.4.18, and 8.1.6, Yaml\Parser::lexInlineStructure() recursed through lexInlineMapping() and lexInlineSequence() for every { and [ of an inline collection, without entering the nesting level that the rest of the parser bounds with maxNestingLevel. A document made of deeply nested inline collections, such as [[[[...]]]], exhausted the stack while it was being lexed: depending on the PHP version and its stack settings, the process crashed or the request ended with a fatal error.
Any code parsing untrusted YAML is affected. That includes #[MapRequestPayload] when the Yaml component is installed and the endpoint does not restrict acceptFormat: a single unauthenticated request with a YAML content type is enough.
This issue affects symfony/yaml through v5.4.53, v6.0.0-BETA1 through v6.4.44, v7.0.0-BETA1 through v7.4.17, and v8.0.0-BETA1 through v8.1.5.
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 | 7.4.18+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 | — |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| Packagist | symfony/symfony | >= 2.0.0, < 5.4.54 | 5.4.54 | GHSA-2v3c-qxhr-7vpv |
| Packagist | symfony/symfony | >= 6.0.0, < 6.4.45 | 6.4.45 | GHSA-2v3c-qxhr-7vpv |
| Packagist | symfony/symfony | >= 7.0.0, < 7.4.18 | 7.4.18 | GHSA-2v3c-qxhr-7vpv |
| Packagist | symfony/symfony | >= 8.0.0, < 8.1.6 | 8.1.6 | GHSA-2v3c-qxhr-7vpv |
| Packagist | symfony/yaml | >= 2.0.0, < 5.4.54 | 5.4.54 | GHSA-2v3c-qxhr-7vpv |
| Packagist | symfony/yaml | >= 6.0.0, < 6.4.45 | 6.4.45 | GHSA-2v3c-qxhr-7vpv |
| Packagist | symfony/yaml | >= 7.0.0, < 7.4.18 | 7.4.18 | GHSA-2v3c-qxhr-7vpv |
| Packagist | symfony/yaml | >= 8.0.0, < 8.1.6 | 8.1.6 | GHSA-2v3c-qxhr-7vpv |
Advisories 1
- WID-SEC-2026-4047 Snipe-IT: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 4, 2026