Answer in brief
CVE-2026-109413 records a High severity (CVSS 8.7) vulnerability in Symfony: Unbounded Recursion in the YAML Inline Lexer Lets a Single Document Crash the Process. The current sources do not mark it as known exploited. The current feed maps sensiolabs/symfony/yaml (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 8.7. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps sensiolabs/symfony/yaml (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| sensiolabs/symfony/yamlgeneric | >=0 <v5.4.54 || >=v6.0.0-BETA1 <v6.4.45 || >=v7.0.0-BETA1 <v7.4.18 || >=v8.0.0-BETA1 <v8.1.6 | v5.4.54, v6.4.45, v7.4.18, v8.1.6 |
Published upstream
Oct 15, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 15, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Oct 15, 2026
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.
Quoted source text, attributed separately from HOL analysis.