PocketMine-MP server crash with certain invalid JSON payloads in `LoginPacket` due to dependency vulnerability (3rd time)
Impact
An attacker could crash PocketMine-MP by sending malformed JSON in LoginPacket.
netresearch/jsonmapper allows objects to be hydrated from scalar types in JSON. However, due to the lack of validation in the code for this feature, it may output improperly initialized objects if applied to objects whose constructors don't handle the input values.
Code handling these objects in PocketMine-MP could then crash due to @required properties not being set within the objects.
In addition, because JsonMapper does not respect bStrictObjectTypes when processing arrays, it's not possible to avoid the issue by disabling the feature.
Due to the relatively high number of security issues arising from unexpected behaviour in JsonMapper, the team is exploring options to replace it.
Patches
In the meantime, the issue was fixed by pmmp/netresearch-jsonmapper@b96a209f9e8b76b899a0d0918493cd87eb3c02a7 and 6872661fd03649cc7a8762c41c16e9ee5a4de1c9.
Workarounds
Detecting the malicious data that triggers this issue is of rather high difficulty, so it's not likely that a plugin would be able to easily remediate this.
References
https://github.com/cweiske/jsonmapper/pull/225 https://github.com/cweiske/jsonmapper/issues/226
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Composer package | pocketmine/pocketmine-mp | < 5.11.1 | 5.11.1 |
References
- https://github.com/pmmp/PocketMine-MP/security/advisories/GHSA-h6j3-j35f-v2x7
- https://github.com/cweiske/jsonmapper/issues/226
- https://github.com/cweiske/jsonmapper/pull/225
- https://github.com/pmmp/PocketMine-MP/commit/6872661fd03649cc7a8762c41c16e9ee5a4de1c9
- https://github.com/pmmp/netresearch-jsonmapper/commit/b96a209f9e8b76b899a0d0918493cd87eb3c02a7
- https://github.com/pmmp/PocketMine-MP
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H- Weakness (CWE)
-- Platform
- Composer
- Package
pocketmine/pocketmine-mp- Disclosed
- 06.03.2024
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-h6j3-j35f-v2x7 - CC BY 4.0
Vulnerability history: pocketmine/pocketmine-mp
All published vulnerabilities of this package (Composer package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 30
- First → latest
- 11.2020 04.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 20
- Medium 8
- Low 2
Disclosures per year
- 2020: 1
- 2021: 1
- 2022: 11
- 2023: 8
- 2024: 2
- 2025: 2
- 2026: 5
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PocketMine-MP server crash with certain invalid JSON payloads in `LoginPacket` due to dependency vulnerability (3rd time) this entry
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