Answer in brief
CVE-2026-45304 records a High severity (CVSS 7.5) vulnerability in Symfony: YAML Parser Exponential Memory Allocation via Recursive Collection-Alias Expansion ("Billion Laughs"). The current sources do not mark it as known exploited. The current feed maps symfony/symfony (generic), 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.
Answer in brief
CVE-2026-45304 records a High severity (CVSS 7.5) vulnerability in Symfony: YAML Parser Exponential Memory Allocation via Recursive Collection-Alias Expansion ("Billion Laughs"). The current sources do not mark it as known exploited. The current feed maps symfony/symfony (generic), 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 7.5. 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 symfony/symfony (generic), symfony/yaml (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| symfony/symfonygeneric | < 5.4.52 || >= 6.0.0-BETA1, < 6.4.40 || >= 7.0.0-BETA1, < 7.4.12 || >= 8.0.0-BETA1, < 8.0.12 | Not reported |
| symfony/yamlgeneric | < 5.4.52 || >= 6.0.0-BETA1, < 6.4.40 || >= 7.0.0-BETA1, < 7.4.12 || >= 8.0.0-BETA1, < 8.0.12 | Not reported |
Published upstream
Jul 14, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Jul 15, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jul 15, 2026
Symfony is a PHP framework for web and console applications and a set of reusable PHP components. Prior to 5.4.52, 6.4.40, 7.4.12, and 8.0.12, Symfony\Component\Yaml\Parser resolved YAML collection aliases recursively, allowing a small untrusted YAML input to expand into a multi-gigabyte structure and exhaust memory. This issue is fixed in versions 5.4.52, 6.4.40, 7.4.12, and 8.0.12.
Quoted source text, attributed separately from HOL analysis.
CVSS is 7.5. 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 symfony/symfony (generic), symfony/yaml (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| symfony/symfonygeneric | < 5.4.52 || >= 6.0.0-BETA1, < 6.4.40 || >= 7.0.0-BETA1, < 7.4.12 || >= 8.0.0-BETA1, < 8.0.12 | Not reported |
| symfony/yamlgeneric | < 5.4.52 || >= 6.0.0-BETA1, < 6.4.40 || >= 7.0.0-BETA1, < 7.4.12 || >= 8.0.0-BETA1, < 8.0.12 | Not reported |
Published upstream
Jul 14, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Jul 15, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jul 15, 2026
Symfony is a PHP framework for web and console applications and a set of reusable PHP components. Prior to 5.4.52, 6.4.40, 7.4.12, and 8.0.12, Symfony\Component\Yaml\Parser resolved YAML collection aliases recursively, allowing a small untrusted YAML input to expand into a multi-gigabyte structure and exhaust memory. This issue is fixed in versions 5.4.52, 6.4.40, 7.4.12, and 8.0.12.
Quoted source text, attributed separately from HOL analysis.