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.
CVSS Details
- CVSS 3.1 Base Score: 7.2
- CVSS 3.0 Vector: (CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H)
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