GHSA-h6j3-j35f-v2x7 is a high-severity (CVSS 7.5) Deserialization of Untrusted Data vulnerability in pocketmine/pocketmine-mp. A fix is available for pocketmine/pocketmine-mp — see the affected versions and patch details below.
PocketMine-MP server crash with certain invalid JSON payloads in `LoginPacket` due to dependency vulnerability (3rd time)
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- 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-h6j3-j35f-v2x7.
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-h6j3-j35f-v2x7 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 377,166 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
pocketmine/pocketmine-mpReal-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
An attacker could crash PocketMine-MP by sending malformed JSON in LoginPacket.
netresearch/jsonmapper allows objects to be hydrated from scalar types in JSON. However, due to the lack of validation in the code for this feature, it may output improperly initialized objects if applied to objects whose constructors don't handle the input values.
Code handling these objects in PocketMine-MP could then crash due to @required properties not being set within the objects.
In addition, because JsonMapper does not respect bStrictObjectTypes when processing arrays, it's not possible to avoid the issue by disabling the feature.
Due to the relatively high number of security issues arising from unexpected behaviour in JsonMapper, the team is exploring options to replace it.
Patches
In the meantime, the issue was fixed by pmmp/netresearch-jsonmapper@b96a209f9e8b76b899a0d0918493cd87eb3c02a7 and 6872661fd03649cc7a8762c41c16e9ee5a4de1c9.
Workarounds
Detecting the malicious data that triggers this issue is of rather high difficulty, so it's not likely that a plugin would be able to easily remediate this.
References
https://github.com/cweiske/jsonmapper/pull/225 https://github.com/cweiske/jsonmapper/issues/226
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | pocketmine/pocketmine-mp | all versions | 5.11.1composer require pocketmine/pocketmine-mp:^5.11.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for pocketmine/pocketmine-mp, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update pocketmine/pocketmine-mp to 5.11.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-h6j3-j35f-v2x7 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 GHSA-h6j3-j35f-v2x7 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-h6j3-j35f-v2x7. 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-h6j3-j35f-v2x7 in your dependencies?
O3 Security finds GHSA-h6j3-j35f-v2x7 across Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.