Improper input validation in Mybb
CVE-2019-12831
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.
Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)
EPSS: 0.015 (71.5th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 7.2 (High). Vector: CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H.
Affected products
- Mybb
- N/a — versions n/a
Weakness classification (CWE)
References
- cve@mitre.org (Exploit, x_refsource_MISC, Vendor Advisory)
- cve@mitre.org (x_refsource_MISC, Release Notes, Vendor Advisory)
Frequently asked questions
- What is CVE-2019-12831?
- CVE-2019-12831 is a high-severity vulnerability in Mybb, classified under Improper Input Validation. CVSS score: 7.2/10. Published 2019-06-15.
- How severe is CVE-2019-12831?
- High severity. CVSS v3 base score is 7.2 out of 10.