CVE-2026-45304 (GCVE-0-2026-45304)
Vulnerability from cvelistv5 – Published: 2026-07-14 18:48 – Updated: 2026-07-14 19:13
VLAI
EPSS
VEX
Title
Symfony: YAML Parser Exponential Memory Allocation via Recursive Collection-Alias Expansion ("Billion Laughs")
Summary
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.
Severity
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-07-14 19:13 UTC
CWE
- CWE-776 - Improper Restriction of Recursive Entity References in DTDs ('XML Entity Expansion')
Assigner
References
6 references
| URL | Tags |
|---|---|
| https://github.com/symfony/symfony/security/advis… | x_refsource_CONFIRM |
| https://github.com/symfony/symfony/commit/e77391b… | x_refsource_MISC |
| https://github.com/symfony/symfony/releases/tag/v5.4.52 | x_refsource_MISC |
| https://github.com/symfony/symfony/releases/tag/v6.4.40 | x_refsource_MISC |
| https://github.com/symfony/symfony/releases/tag/v7.4.12 | x_refsource_MISC |
| https://github.com/symfony/symfony/releases/tag/v8.0.12 | x_refsource_MISC |
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| symfony | symfony |
Affected:
< 5.4.52
Affected: >= 6.0.0-BETA1, < 6.4.40 Affected: >= 7.0.0-BETA1, < 7.4.12 Affected: >= 8.0.0-BETA1, < 8.0.12 |
guessed | |
| symfony | yaml |
Affected:
< 5.4.52
Affected: >= 6.0.0-BETA1, < 6.4.40 Affected: >= 7.0.0-BETA1, < 7.4.12 Affected: >= 8.0.0-BETA1, < 8.0.12 |
guessed |
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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