vBulletin through 5.5.4 mishandles external URLs within the /core/vb/vurl.php file and the /core/vb/vurl directories.
https://forum.vbulletin.com/forum/vbulletin-announcements/vbulletin-announcements_aa/4423391-vbulletin-5-5-5-alpha-4-available-for-download
Source: Mitre, NVD
Published: 2019-10-04
Updated: 2019-10-10
Base Score: 6.4
Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:N
Severity: Medium
Base Score: 6.5
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N