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Improperly checked dropped item count leading to server crash

High
dktapps published GHSA-h87r-f4vc-mchv May 30, 2023

Package

composer pocketmine/pocketmine-mp (Composer)

Affected versions

< 4.18.1

Patched versions

4.18.1

Description

Impact

In 4.18.0, the network handling of inventories was completely revamped. Due to this, a bug was introduced which allowed players to request that the server drop more of an item than they had available in their hotbar.

This did not lead to any duplication issues, but instead led to a server crash, and is believed to have been exploited in the wild.

Patches

This was fixed in 5897476, which was released in 4.18.1.

Workarounds

Handle InventoryTransactionPacket in DataPacketReceiveEvent, and verify that the item count dropped isn't more than the available item count. However, it's complicated to do this, so it's not recommended.

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVE ID

No known CVE

Weaknesses

No CWEs

Credits