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Unhandled exception when decoding form response JSON

High severity GitHub Reviewed Published Jan 21, 2022 in pmmp/PocketMine-MP • Updated Jan 11, 2023

Package

composer pocketmine/pocketmine-mp (Composer)

Affected versions

>= 4.0.0, < 4.0.7

Patched versions

4.0.7

Description

Impact

When handling form responses from the client (ModalFormResponsePacket), the Minecraft Windows client may send weird JSON that json_decode() can't understand. A workaround for this is implemented in InGamePacketHandler::stupid_json_decode().

An InvalidArgumentException is thrown by this function when it fails to fix an error found in the JSON, which is not caught by the caller. This leads to a server crash.

Patches

56fe71d939c38fe14e18a31a673a9331bcc0e4ca

Workarounds

A plugin may handle DataPacketReceiveEvent, capture ModalFormResponsePacket and run the provided JSON through stupid_json_decode.

Note that this requires copying the body of the function to a plugin, since the function is currently private.

For more information

If you have any questions or comments about this advisory:

References

@dktapps dktapps published to pmmp/PocketMine-MP Jan 21, 2022
Reviewed Jan 21, 2022
Published to the GitHub Advisory Database Jan 21, 2022
Last updated Jan 11, 2023

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

Weaknesses

No CWEs

CVE ID

No known CVE

GHSA ID

GHSA-wjfq-88q2-r34j

Source code

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