GHSA-h6rj-3m53-887h is a high-severity (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in pocketmine/pocketmine-mp. A fix is available for pocketmine/pocketmine-mp — see the affected versions and patch details below.
PocketMine-MP: LogDoS by large complex unknown property logging in clientData in LoginPacket
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for GHSA-h6rj-3m53-887h.
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-h6rj-3m53-887h 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
Attackers can put large and/or complex structures as a value to an unknown property in the clientData JWT body in the Minecraft LoginPacket, causing the server to generate very long log messages.
Additionally, the property name is logged without any length limitations or sanitization, which can also be abused for LogDoS.
This may be used to spam the log/console, waste CPU time serializing the offending structure, and potentially to crash the server entirely.
This happens because the JsonMapper instance used to process the JWT body is configured to warn on unexpected properties instead of rejecting them outright. While this behaviour increases flexibility for random changes introduced by Microsoft, it also creates vulnerabilities if not handled carefully.
This vulnerability affects PocketMine-MP servers exposed to a public network where unknown actors may have access.
PoC
-
Connect to the server using a custom client.
-
Send a Minecraft
LoginPacketcontaining an unexpected JSON property (e.g., invalid_key) within the ClientData. -
Set the value of invalid_key to a highly recursive or massive object structure (e.g., an array containing millions of elements or deeply nested arrays).
-
The server hits the
warnUndefinedJsonPropertyHandler, which attempts to var_export the malicious object, leading to an Out-of-Memory crash.
A := make([]interface{}, 1)
ptr := &A
for i := 0; i < 500; i++ {
next := make([]interface{}, 1000)
(*ptr)[0] = next
ptr = &next
}
data := make([]int, 2000000)
for i := 0; i < 100; i++ {
data[i] = i
}
(*ptr)[0] = data
d.PlayFabID = A
Patches
The issue was addressed in https://github.com/pmmp/PocketMine-MP/commit/87d1c0cea09d972fd4c2fafb84dac2ecab7649f0 by removing the relevant var_export and limiting the length of the logged property name to 80 characters.
Workarounds
Plugins can handle DataPacketReceiveEvent to capture LoginPacket, and pre-process the clientData JWT to ensure it doesn't have any unusual properties in it. This can be achieved using JsonMapper (see the original affected code below) and setting the bExceptionOnUndefinedProperty flag to true. A JsonMapper_Exception will be thrown if the JWT is problematic.
However, it's important to caveat that this approach may cause login failures if any unexpected properties appear out of the blue in future versions (which has happened in the past).
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | pocketmine/pocketmine-mp | all versions | 5.41.1composer require pocketmine/pocketmine-mp:^5.41.1 |
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 5.41.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-h6rj-3m53-887h 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-h6rj-3m53-887h can be triaged on real exposure rather than presence alone.
Tailored to GHSA-h6rj-3m53-887h. 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-h6rj-3m53-887h in your dependencies?
O3 Security finds GHSA-h6rj-3m53-887h across Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.