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High, CVSS 7.5

Buffer length underflow in LoginPacket causing unchecked exceptions to be thrown

GHSA-5jfw-35xp-5m42

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (pocketmine/bedrock-protocol 8.0.2), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS
No dated EPSS signal available.
Source description

As published by the source; long descriptions are shortened.

Impact LoginPacket uses BinaryStream-getLInt() to read the lengths of JSON payloads it wants to decode. Unfortunately, BinaryStream-getLInt() returns a signed integer, meaning that a malicious client can craft a packet with a large uint32 value for payload buffer size (which would be interpreted as a negative signed int32), causing BinaryStream-get() to throw an exception. In the context of PocketMine-MP, this leads to a server crash when the vulnerability is exploited. Patches e3fce7632b94e83fd6a518a87dcaf6a11681c4ac Workarounds This can be worked around by registering a custom LoginPacket implementation into PacketPool which overrides this code to patch it. For more information Email us at team@pmmp.io

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 1 · created ·

    Published from ghsa record GHSA-5jfw-35xp-5m42

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: GHSA-5jfw-35xp-5m42

Advisory: Buffer length underflow in LoginPacket causing unchecked exceptions to be thrown
IDs: GHSA-5jfw-35xp-5m42
Record: https://patchnext.com/advisories/ghsa-5jfw-35xp-5m42 (revision 1, source checked 26 Oct 2026, 13:56 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: pocketmine/bedrock-protocol 8.0.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist pocketmine/bedrock-protocol: affected < 8.0.2; fixed in 8.0.2

## Suggested inspection (read-only)
- Packagist pocketmine/bedrock-protocol: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on pocketmine/bedrock-protocol.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-5jfw-35xp-5m42 (GitHub-reviewed advisory GHSA-5jfw-35xp-5m42 lists affected ranges: Packagist pocketmine/bedrock-protocol >=0 <8.0.2)

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