Summary
PocketMine MP vulnerable to uncontrolled resource consumption via mismatched type of 'InventoryTransactionPacket'
Workarounds
Plugins can handle DataPacketReceiveEvent for InventoryTransactionPacket and check if the type is MismatchTransactionData. If it is, apply some kind of rate limit (e.g. max 1 per tick).
Impact
A "mismatch" type InventoryTransactionPacket is sent by the client to request a resync of all currently open inventories.
Since PocketMine-MP does not rate-limit these "mismatch" transactions, and the syncing of inventories is not deferred until, e.g. the end of the current tick, they can be used as a very cheap bandwidth multiplier by making the server send out many MB of data (network serialized inventory items can be very large, especially when dealing with large amounts of NBT).
This is not currently known to have been exploited in the wild.
Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service. Typical impact: denial of service.
GHSA-42QM-8V8M-M78C has a CVSS score of 5.3 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (4.18.0-ALPHA2); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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This problem was fixed in 4.18.0-ALPHA2 by ca6d51498f12427a947467da8fcad7811418e6cc alongside the introduction of the ItemStackRequest system implementation.
Frequently Asked Questions
- What is GHSA-42QM-8V8M-M78C? GHSA-42QM-8V8M-M78C is a medium-severity uncontrolled resource consumption vulnerability in pocketmine/pocketmine-mp (composer), affecting versions < 4.18.0-ALPHA2. It is fixed in 4.18.0-ALPHA2. Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service.
- How severe is GHSA-42QM-8V8M-M78C? GHSA-42QM-8V8M-M78C has a CVSS score of 5.3 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of pocketmine/pocketmine-mp are affected by GHSA-42QM-8V8M-M78C? pocketmine/pocketmine-mp (composer) versions < 4.18.0-ALPHA2 is affected.
- Is there a fix for GHSA-42QM-8V8M-M78C? Yes. GHSA-42QM-8V8M-M78C is fixed in 4.18.0-ALPHA2. Upgrade to this version or later.
- Is GHSA-42QM-8V8M-M78C exploitable, and should I be worried? Whether GHSA-42QM-8V8M-M78C is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether GHSA-42QM-8V8M-M78C is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix GHSA-42QM-8V8M-M78C? Upgrade
pocketmine/pocketmine-mpto 4.18.0-ALPHA2 or later.