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CVE-2026-61511 - a critical vulnerability in vBulletin that allows an unauthenticated attacker to execute arbitrary code on a remote server.
vBulletin 5.x through 5.7.5 and 6.x through 6.2.1 contains an eval injection vulnerability in the vB5TemplateRuntime::runMaths() method within the template runtime that allows unauthenticated remote attackers to execute arbitrary PHP code by supplying crafted input through the pagenav[pagenumber] parameter. Attackers can exploit the insufficiently restrictive regex filter by using phpfuck-style encoding with permitted characters to inject and execute arbitrary PHP code via the unauthenticated ajax/render template route without any authentication.
A vulnerability was found in vBulletin 6.x. This impacts an unknown function of the component Login. Performing a manipulation results in cross site scripting. It is possible to initiate the attack remotely. The exploit has been made public and could be used. VulDB is withholding an extended redistribution of exploit details to prevent simplified exploitation. The vendor was contacted early about this disclosure but did not respond in any way.
vBulletin 3.8.7 is vulnerable to a denial-of-service condition via the misc.php?do=buddylist endpoint. If an authenticated user has a sufficiently large buddy list, processing the list can consume excessive memory, exhausting system resources and crashing the forum.
Certain vBulletin versions might allow attackers to execute arbitrary PHP code by abusing Template Conditionals in the template engine. By crafting template code in an alternative PHP function invocation syntax, such as the "vardump"("test") syntax, attackers can bypass security checks and execute arbitrary PHP code, as exploited in the wild in May 2025.
vBulletin 5.0.0 through 5.7.5 and 6.0.0 through 6.0.3 allows unauthenticated users to invoke protected API controllers' methods when running on PHP 8.1 or later, as demonstrated by the /api.php?method=protectedMethod pattern, as exploited in the wild in May 2025.
A cross-site scripting (XSS) vulnerability in the Admin Control Panel of vBulletin 5.7.5 and 6.0.0 allows attackers to execute arbitrary web scripts or HTML via the /login.php?do=login url parameter.
vBulletin before 5.6.9 PL1 allows an unauthenticated remote attacker to execute arbitrary code via a crafted HTTP request that triggers deserialization. This occurs because verifyserialized checks that a value is serialized by calling unserialize and then checking for errors. The fixed versions are 5.6.7 PL1, 5.6.8 PL1, and 5.6.9 PL1.
vBulletin 5.5.4 through 5.6.2 allows remote command execution via crafted subWidgets data in an ajax/render/widgettabbedcontainertabpanel request. NOTE: this issue exists because of an incomplete fix for CVE-2019-16759. ALSO NOTE: CVE-2020-7373 is a duplicate of CVE-2020-17496. CVE-2020-17496 is the preferred CVE ID to track this vulnerability.
The Admin CP in vBulletin 5.6.3 allows XSS via an Occupation Title or Description to User Profile Field Manager.
The Admin CP in vBulletin 5.6.3 allows XSS via an Announcement Title to Channel Manager.
The Admin CP in vBulletin 5.6.3 allows XSS via a Junior Member Title to User Title Manager.
The Admin CP in vBulletin 5.6.3 allows XSS via a Style Options Settings Title to Styles Manager.
The Admin CP in vBulletin 5.6.3 allows XSS via a Title of a Child Help Item in the Login/Logoff part of the User Manual.
The Admin CP in vBulletin 5.6.3 allows XSS via the admincp/search.php?do=dosearch URI.
The Admin CP in vBulletin 5.6.3 allows XSS via the Paid Subscription Email Notification field in the Options.
The Admin CP in vBulletin 5.6.3 allows XSS via a Rank Type to User Rank Manager.
The Admin CP in vBulletin 5.6.3 allows XSS via a Smilie Title to Smilies Manager.
The Admin CP in vBulletin 5.6.3 allows XSS via an admincp/attachment.php&do=rebuild&type= URI.
vBulletin 5.5.4 through 5.6.2 allows remote command execution via crafted subWidgets data in an ajax/render/widgettabbedcontainertabpanel request. NOTE: this issue exists because of an incomplete fix for CVE-2019-16759.
vBulletin before 5.5.6pl1, 5.6.0 before 5.6.0pl1, and 5.6.1 before 5.6.1pl1 has incorrect access control.
vBulletin 5.5.4 allows SQL Injection via the ajax/api/hook/getHookList or ajax/api/widget/getWidgetList where parameter.
vBulletin through 5.5.4 mishandles custom avatars.
vBulletin before 5.5.4 allows clickjacking.
vBulletin through 5.5.4 mishandles external URLs within the /core/vb/vurl.php file and the /core/vb/vurl directories.
vBulletin 5.x through 5.5.4 allows remote command execution via the widgetConfig[code] parameter in an ajax/render/widgetphp routestring request.
vBulletin 5.4.3 has an Open Redirect.
vBulletin 3.x.x and 4.2.x through 4.2.5 has an open redirect via the redirector.php url parameter.