message/externallib.php in Moodle through 2.5.9, 2.6.x before 2.6.7, 2.7.x before 2.7.4, and 2.8.x before 2.8.2 allows remote authenticated users to bypass a messaging-disabled setting via a web-services request, as demonstrated by a people-search request.

tag/user.php in Moodle through 2.5.9, 2.6.x before 2.6.9, 2.7.x before 2.7.6, and 2.8.x before 2.8.4 does not consider the moodle/tag:flag capability before proceeding with a flaginappropriate action, which allows remote authenticated users to bypass intended access restrictions via the "Flag as inappropriate" feature.

lib/navigationlib.php in Moodle through 2.5.9, 2.6.x before 2.6.11, 2.7.x before 2.7.8, and 2.8.x before 2.8.6 allows remote authenticated users to obtain sensitive course-structure information by leveraging access to a student account with a suspended enrolment.

calendar/externallib.php in Moodle through 2.5.9, 2.6.x before 2.6.7, 2.7.x before 2.7.4, and 2.8.x before 2.8.2 allows remote authenticated users to obtain sensitive calendar-event information via a web-services request.

mod/quiz/db/access.php in Moodle through 2.5.9, 2.6.x before 2.6.11, 2.7.x before 2.7.8, and 2.8.x before 2.8.6 does not set the RISK_XSS bit for graders, which allows remote authenticated users to conduct cross-site scripting (XSS) attacks via crafted gradebook feedback during manual quiz grading.

mod/lti/ajax.php in Moodle through 2.5.9, 2.6.x before 2.6.7, 2.7.x before 2.7.4, and 2.8.x before 2.8.2 does not consider the moodle/course:manageactivities and mod/lti:addinstance capabilities before proceeding with registered-tool list searches, which allows remote authenticated users to obtain sensitive information via requests to the LTI Ajax service.

login/confirm.php in Moodle through 2.5.9, 2.6.x before 2.6.11, 2.7.x before 2.7.8, and 2.8.x before 2.8.6 allows remote authenticated users to bypass intended login restrictions by leveraging access to an unconfirmed suspended account.

message/index.php in Moodle through 2.5.9, 2.6.x before 2.6.9, 2.7.x before 2.7.6, and 2.8.x before 2.8.4 does not consider the moodle/site:readallmessages capability before accessing arbitrary conversations, which allows remote authenticated users to obtain sensitive personal-contact and unread-message-count information via a modified URL.

Cross-site scripting (XSS) vulnerability in the external_format_text function in lib/externallib.php in Moodle through 2.5.9, 2.6.x before 2.6.11, 2.7.x before 2.7.8, and 2.8.x before 2.8.6 allows remote authenticated users to inject arbitrary web script or HTML into an external application via a crafted string that is visible to web services.

Multiple cross-site request forgery (CSRF) vulnerabilities in (1) editcategories.html and (2) editcategories.php in the Glossary module in Moodle through 2.5.9, 2.6.x before 2.6.7, 2.7.x before 2.7.4, and 2.8.x before 2.8.2 allow remote attackers to hijack the authentication of unspecified victims.