GHSA-699q-wcff-g9mj is a high-severity (CVSS 8.9) Deserialization of Untrusted Data vulnerability in yiisoft/yii2. 4 public exploit references exist, so weaponization risk is real. O3 Security confirms whether GHSA-699q-wcff-g9mj is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Unsafe deserialization in Yii 2
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
GHSA-699q-wcff-g9mj plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE sits: patch-first territory.
Where this sits among everything scored
Of 365,017 CVEs with a current EPSS score, this one falls in the 50–90% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
yiisoft/yii2Real-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
Impact
Remote code execution in case application calls unserialize() on user input containing specially crafted string.
Patches
2.0.38
Workarounds
Add the following to BatchQueryResult.php:
public function __sleep()
{
throw new \BadMethodCallException('Cannot serialize '.__CLASS__);
}
public function __wakeup()
{
throw new \BadMethodCallException('Cannot unserialize '.__CLASS__);
}
For more information
If you have any questions or comments about this advisory, contact us through security form.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | yiisoft/yii2 | all versions | 2.0.38 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for yiisoft/yii2. 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 yiisoft/yii2 to 2.0.38 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-699q-wcff-g9mj 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-699q-wcff-g9mj 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-699q-wcff-g9mj. 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-699q-wcff-g9mj in your dependencies?
O3 detects GHSA-699q-wcff-g9mj across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.