GHSA-c2p3-7m5p-cv8x
Fix: symfony/symfony@914f427GHSA-c2p3-7m5p-cv8x is a CWE-674 vulnerability in symfony/yaml. O3 Security confirms whether GHSA-c2p3-7m5p-cv8x is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Symfony hardened the parser when handling untrusted input
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-c2p3-7m5p-cv8x.
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.
Real-World Exposure
symfony/yaml🐘symfony/symfony🐘symfony/symfony🐘symfony/symfony🐘symfony/symfony🐘symfony/yaml🐘symfony/yaml🐘symfony/yamlReal-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
Description
Symfony\Component\Yaml\Parser is the entry point for parsing YAML strings into PHP values via Yaml::parse(). When the parser is exposed to attacker-controlled input, deeply nested mappings or sequences cause both the block-level (Parser::parseBlock()) and inline (Inline::parseSequence() / Inline::parseMapping()) parsers to recurse without a depth limit. A crafted document exhausts the PHP stack and crashes the worker.
Resolution
The Parser now tracks recursion depth in a shared ParserState object across both block-level and inline parsing, with a default limit of 128. The limit is configurable via a new $maxNestingLevel argument on Parser::__construct(), Yaml::parse() and Yaml::parseFile().
The patch for this issue is available here for branch 5.4.
Credits
Symfony would like to thank Pietro Tirenna (Shielder) for reporting the issue and Nicolas Grekas for fixing it.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | symfony/yaml | all versions | 5.4.52 |
| 🐘Packagist | symfony/symfony | all versions | 5.4.52 |
| 🐘Packagist | symfony/symfony | ≥ 6.0.0&&< 6.4.40 | 6.4.40 |
| 🐘Packagist | symfony/symfony | ≥ 7.0.0&&< 7.4.12 | 7.4.12 |
| 🐘Packagist | symfony/symfony | ≥ 8.0.0&&< 8.0.12 | 8.0.12 |
| 🐘Packagist | symfony/yaml | ≥ 6.0.0&&< 6.4.40 | 6.4.40 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for symfony/yaml. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update symfony/yaml to 5.4.52 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-c2p3-7m5p-cv8x 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 pinpoints whether GHSA-c2p3-7m5p-cv8x is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-c2p3-7m5p-cv8x. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-c2p3-7m5p-cv8x in your dependencies?
O3 detects GHSA-c2p3-7m5p-cv8x across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.