{"id":"CVE-2019-12831","aliases":["EUVD-2019-4411","GHSA-76pq-5fjf-j6xg"],"status":"published","title":"In MyBB before 1.8.21, an attacker can abuse a default behavior of MySQL on many systems (that...","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.","severity":{"version":"3.0","score":7.2,"vector":"CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H","level":"high","assessor":"primary","from":"nvd"},"epss":{"day":"2026-11-09","score":0.01467,"percentile":0.73892,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-20"],"published":"2019-06-15T17:05:08Z","modified":"2026-06-17T02:15:34Z","products":[{"vendor":"mybb","product":"mybb"}],"references":[{"url":"https://blog.ripstech.com/2019/mybb-stored-xss-to-rce/","tags":["x_refsource_MISC","x_transferred","Exploit","Vendor Advisory"]},{"url":"https://blog.mybb.com/2019/06/10/mybb-1-8-21-released-security-maintenance-release/","tags":["x_refsource_MISC","x_transferred","Release Notes","Vendor Advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2019-12831"},{"url":"https://blog.mybb.com/2019/06/10/mybb-1-8-21-released-security-maintenance-release"},{"url":"https://blog.ripstech.com/2019/mybb-stored-xss-to-rce"},{"url":"https://github.com/advisories/GHSA-76pq-5fjf-j6xg"}],"sources":{"cve":[{"id":"CVE-2019-12831","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.","status":"published","published":"2019-06-15T17:05:08Z","modified":"2024-08-04T23:32:55.221Z","updated_at":"2026-11-02T14:20:24.025419Z"}],"euvd":[{"id":"EUVD-2019-4411","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.","status":"published","published":"2019-06-15T17:05:08Z","modified":"2024-08-04T23:32:55Z","updated_at":"2026-11-03T02:40:44.884887Z"}],"ghsa":[{"id":"GHSA-76pq-5fjf-j6xg","title":"In MyBB before 1.8.21, an attacker can abuse a default behavior of MySQL on many systems (that...","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.","status":"published","published":"2022-05-24T16:48:06Z","modified":"2024-04-04T00:58:23Z","cvss":[{"version":"3.0","score":7.2,"vector":"CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H","level":"high"}],"cwes":["CWE-20"],"updated_at":"2026-11-02T14:55:53.858593Z"}],"nvd":[{"id":"CVE-2019-12831","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.","status":"published","published":"2019-06-15T18:29:00.283Z","modified":"2026-06-17T02:15:34.817Z","cvss":[{"version":"3.0","score":7.2,"vector":"CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H","level":"high","assessor":"primary"},{"version":"2.0","score":6.5,"vector":"AV:N/AC:L/Au:S/C:P/I:P/A:P","level":"medium","assessor":"primary"}],"cwes":["CWE-20"],"updated_at":"2026-11-02T14:05:16.285679Z"}]}}