Auth bypass in Cloudburstmc Protocol

CVE-2026-45289

CloudburstMC Protocol is a protocol library for Minecraft Bedrock Edition. Prior to version 3.0.0.Beta12-20260420.182526-15, CloudburstMC Protocol is partially missing validation for FULL type authentication tokens (Cloudburst/Protocol). This vulnerability impacts publicly accessible software depending on the affected versions of Protocol, specifically the EncryptionUtils methods to validate auth payloads for FULL type tokens. This issue has been patched in version 3.0.0.Beta12-20260420.182526-15.

Vulnerability class: Broken Authentication

Published · last modified .

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.

EPSS exploit prediction

EPSS: 0.002 (12.4th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 12th percentile — 12.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-45289: held from 0.001 to 0.002.

EPSS over last 30 days · oldest: 0.001 · newest: 0.002 · change: +0.001

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-45289?
CVE-2026-45289 is a medium-severity vulnerability in Cloudburstmc Protocol, classified under Improper Authentication. CVSS score: 5.3/10. Published 2026-06-02.
How severe is CVE-2026-45289?
Medium severity. CVSS v3 base score is 5.3 out of 10.