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CVE-2019-12831

7.2 · HIGH

In MyBB before 1.8.21, an attacker can abuse a default behavior of MySQL on many systems (that leads to truncation of strings that are too long for a database column) to create a PHP shell in the c…

Published Jun 15, 2019CWE-20EPSS 1.47%

Overview

CVE-2019-12831 is a high-severity vulnerability. It was published on June 15, 2019 and has a CVSS 3.0 base score of 7.2 (HIGH).

This vulnerability has a CVSS 3.0 base score of 7.2, rated HIGH. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

Technical description

In MyBB before 1.8.21, an attacker can abuse a default behavior of MySQL on many systems (that leads to truncation of strings that are too long for a database column) to create a PHP shell in the cache directory of a targeted forum via a crafted XML import, as demonstrated by truncation of aaaaaaaaaaaaaaaaaaaaaaaaaa.php.css to aaaaaaaaaaaaaaaaaaaaaaaaaa.php with a 30-character limit, aka theme import stylesheet name RCE.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refblog.mybb.com/2019/06/10/mybb-1-8-21-released-security-maintenance-release/Refblog.ripstech.com/2019/mybb-stored-xss-to-rce/Refblog.mybb.com/2019/06/10/mybb-1-8-21-released-security-maintenance-release/Refblog.ripstech.com/2019/mybb-stored-xss-to-rce/

How CyberStrike helps

Frequently asked questions

What is CVE-2019-12831?

CVE-2019-12831 is a high-severity vulnerability. It was published on June 15, 2019 and has a CVSS 3.0 base score of 7.2 (HIGH).

How severe is CVE-2019-12831?

This vulnerability has a CVSS 3.0 base score of 7.2, rated HIGH. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2019-12831?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2019-12831?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2019-12831 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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