CVE-2013-4751 — symfony/validator
HIGHCVE-2013-4751 is a high-severity (CVSS 8.1) Improper Input Validation vulnerability in symfony/validator. A fix is available for symfony/validator — see the affected versions and patch details below.
Symfony collectionCascaded and collectionCascadedDeeply fields security bypass
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2013-4751 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 376,715 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
symfony/validator🐘symfony/validator🐘symfony/validator🐘symfony/validator🐘symfony/symfony🐘symfony/symfony🐘symfony/symfony🐘symfony/symfonyReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
When using the Validator component, if Symfony\\Component\\Validator\\Mapping\\Cache\\ApcCache is enabled (or any other cache implementing Symfony\\Component\\Validator\\Mapping\\Cache\\CacheInterface), some information is lost during serialization (the collectionCascaded and the collectionCascadedDeeply fields).
As a consequence, arrays or traversable objects stored in fields using the @Valid constraint are not traversed by the validator as soon as the validator configuration is loaded from the cache.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | symfony/validator | ≥ 2.0.0&&< 2.0.24 | 2.0.24composer require symfony/validator:^2.0.24 |
| 🐘Packagist | symfony/validator | ≥ 2.1.0&&< 2.1.12 | 2.1.12composer require symfony/validator:^2.1.12 |
| 🐘Packagist | symfony/validator | ≥ 2.2.0&&< 2.2.5 | 2.2.5composer require symfony/validator:^2.2.5 |
| 🐘Packagist | symfony/validator | ≥ 2.3.0&&< 2.3.3 | 2.3.3composer require symfony/validator:^2.3.3 |
| 🐘Packagist | symfony/symfony | ≥ 2.0.0&&< 2.0.24 | 2.0.24composer require symfony/symfony:^2.0.24 |
| 🐘Packagist | symfony/symfony | ≥ 2.1.0&&< 2.1.12 | 2.1.12composer require symfony/symfony:^2.1.12 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for symfony/validator, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update symfony/validator to 2.0.24 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2013-4751 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2013-4751 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2013-4751. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2013-4751 in your dependencies?
O3 Security finds CVE-2013-4751 across Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.