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GHSA-p62j-hrxm-xcxf

MediumCVSS 6.5 / 10
Published Jan 6, 2022·Last modified Dec 4, 2024
Affected Components(0)

No affected components available

Description

Impact

Players can fill book pages with as many characters as they like; the server does not check this. In addition, the maximum of 50 pages is also not enforced, meaning that players can create "book bombs".

This causes a variety of problems:

  • Oversized NBT on the wire costing excess bandwidth for server and client
  • Server crashes when saving region-based worlds due to exceeding maximum chunk size of 1 MB (PM3-specific)
  • Server crashes if any book page exceeds 32 KiB (due to TAG_String size limit) (PM4-specific)

This does, however, require that an attacker obtain a writable book in the first place in order to exploit the problem.

Patches

The bug has been fixed in 3.26.5 and 4.0.5.

Workarounds

Ban writable books, or use a plugin to cancel PlayerEditBookEvent to cancel the event if strlen(text) > 1024 || mb_strlen(text) > 256.

For more information

If you have any questions or comments about this advisory:

Risk Scores
Base Score
6.5

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker needs basic access or low-level privileges. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a high impact on the availability of the system.

Threat Intelligence
6.0

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
N/A

Probability that this vulnerability will be exploited in the wild within the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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