GHSA-gj94-v4p9-w672 — pocketmine/pocketmine-mp
MEDIUMGHSA-gj94-v4p9-w672 is a medium-severity (CVSS 5.3) Improper Input Validation vulnerability in pocketmine/pocketmine-mp. A fix is available for pocketmine/pocketmine-mp — see the affected versions and patch details below.
Denial-of-service vulnerability processing large chat messages containing many newlines
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-gj94-v4p9-w672.
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-gj94-v4p9-w672 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
PocketMine-MP caps maximum chat message length at 512 Unicode characters, or about 2048 bytes. No more than 2 chat messages may be sent per tick. However, due to legacy reasons, incoming chat message blobs are split by \n, and each part is treated as a separate message, the length of each part is individually checked. The length of the whole message is not checked.
This leads to an exploitable performance issue, in which a malicious client may send a chat packet of several megabytes containing nothing but \n newline characters. The server will parse this into a very large array and spend a long time (several milliseconds) iterating over it for no reason.
Furthermore, due to the lack of sufficient rate limit checks before parsing messages, malicious clients may bombard the server with many thousands of these malicious messages, causing lockups for a significant amount of time (seconds or minutes).
Patches
This bug was addressed in https://github.com/pmmp/PocketMine-MP/commit/df33e179e5d3ff13b56a2d7060bf592b0f797258 by:
- checking the length of the incoming message as a whole before parsing it - it may not be larger than
messageCounter * maxChatMessageSize(messageCounteris decremented once for every message sent) - limiting the maximum number of times a message may be split on newlines before giving up and discarding the message (maximum 3 parts; anything after the first 2 parts is discarded)
Workarounds
Handle DataPacketReceiveEvent and check for these excessive newlines in incoming TextPacket.
For more information
If you have any questions or comments about this advisory:
- Email us at [email protected]
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | pocketmine/pocketmine-mp | all versions | 4.2.10composer require pocketmine/pocketmine-mp:^4.2.10 |
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 4.2.10 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-gj94-v4p9-w672 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-gj94-v4p9-w672 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-gj94-v4p9-w672. 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-gj94-v4p9-w672 in your dependencies?
O3 Security finds GHSA-gj94-v4p9-w672 across Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.