CVE-2021-33790

Name: CVE-2021-33790
Creator: NVD / NIST
Published: 2021-05-31T04:15:08.153+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 2.84%

Last modified Jun 17, 2026

CVE-2021-33790 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. The RebornCore library before 4.7.3 allows remote code execution because it deserializes untrusted data in ObjectInputStream.readObject as part of reborncore.common.network.ExtendedPacketBuffer. An attacker can instantiate any class on the classpath with any data. EPSS estimates a 2.84% chance of exploitation in the next 30 days.

Description

The RebornCore library before 4.7.3 allows remote code execution because it deserializes untrusted data in ObjectInputStream.readObject as part of reborncore.common.network.ExtendedPacketBuffer. An attacker can instantiate any class on the classpath with any data. A class usable for exploitation might or might not be present, depending on what Minecraft modifications are installed.

Metrics

CVSS 3.1

9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

2.84%

84.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-502

Affected Software

Vendor	Product	Versions
Techreborn	Reborncore	<= 3.13.8
Techreborn	Reborncore	>= 3.19.0, < 3.19.5
Techreborn	Reborncore	>= 4.2.0, < 4.2.10
Techreborn	Reborncore	>= 4.7.0, < 4.7.3

References

https://github.com/TechReborn/RebornCore/security/advisories/GHSA-r7pg-4xrf-7mrmThird Party Advisory
https://vuln.ryotak.me/advisories/45Third Party Advisory
https://www.curseforge.com/minecraft/mc-mods/reborncoreProduct, Third Party Advisory
https://github.com/TechReborn/RebornCore/security/advisories/GHSA-r7pg-4xrf-7mrmThird Party Advisory
https://vuln.ryotak.me/advisories/45Third Party Advisory
https://www.curseforge.com/minecraft/mc-mods/reborncoreProduct, Third Party Advisory

Timeline

Published: May 31, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-33790?

How severe is CVE-2021-33790?

CVE-2021-33790 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 2.84% probability of exploitation in the next 30 days.

How do I fix CVE-2021-33790?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-33790?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST