Discourse is an open-source discussion platform. Prior to versions 3.4.3 on the stable branch and 3.5.0.beta3 on the beta branch, the users limit for a DM can be bypassed, thus giving the ability to potentially create a DM with every user from a site in it. This issue has been patched in stable version 3.4.3 and beta version 3.5.0.beta3.

Discourse is an open-source discussion platform. Prior to version 3.1.1 of the stable branch and version 3.2.0.beta1 of the beta and tests-passed branches, a malicious admin could create extremely large icons sprites, which would then be cached in each server process. This may cause server processes to be killed and lead to downtime. The issue is patched in version 3.1.1 of the stable branch and version 3.2.0.beta1 of the beta and tests-passed branches. This is only a concern for multisite installations. No action is required when the admins are trusted.

Discourse is an open-source discussion platform. Prior to version 3.1.1 of the stable branch and version 3.2.0.beta1 of the beta and tests-passed branches, importing a remote theme loads their assets into memory without enforcing limits for file size or number of files. The issue is patched in version 3.1.1 of the stable branch and version 3.2.0.beta1 of the beta and tests-passed branches. There are no known workarounds.

Discourse is an open-source discussion platform. Prior to version 3.1.1 of the stable branch and version 3.2.0.beta1 of the beta and tests-passed branches, a malicious user could add a 2FA or security key with a carefully crafted name to their account and cause a denial of service for other users. The issue is patched in version 3.1.1 of the stable branch and version 3.2.0.beta1 of the beta and tests-passed branches. There are no known workarounds.

Discourse is an open-source discussion platform. Prior to version 3.1.1 of the stable branch and version 3.2.0.beta1 of the beta and tests-passed branches, a malicious user can create an unlimited number of drafts with very long draft keys which may end up exhausting the resources on the server. The issue is patched in version 3.1.1 of the stable branch and version 3.2.0.beta1 of the beta and tests-passed branches. There are no known workarounds.

Discourse is an open source discussion platform. Prior to version 3.0.6 of the stable branch and version 3.1.0.beta7 of the beta and tests-passed branches, information about restricted-visibility topic tags could be obtained by unauthorized users. The issue is patched in version 3.0.6 of the stable branch and version 3.1.0.beta7 of the beta and tests-passed branches.

Discourse is an open source discussion platform. Prior to version 3.0.6 of the stable branch and version 3.1.0.beta7 of the beta and tests-passed branches, in multiple controller actions, Discourse accepts limit params but does not impose any upper bound on the values being accepted. Without an upper bound, the software may allow arbitrary users to generate DB queries which may end up exhausting the resources on the server. The issue is patched in version 3.0.6 of the stable branch and version 3.1.0.beta7 of the beta and tests-passed branches. There are no known workarounds for this vulnerability.

Discourse is an open source discussion platform. Prior to version 3.0.6 of the stable branch and version 3.1.0.beta7 of the beta and tests-passed branches, a malicious user can prevent the defer queue from proceeding promptly on sites hosted in the same multisite installation. The issue is patched in version 3.0.6 of the stable branch and version 3.1.0.beta7 of the beta and tests-passed branches. There are no known workarounds for this vulnerability. Users of multisite configurations should upgrade.

Discourse is an open source discussion platform. Prior to version 3.0.6 of the stable branch and version 3.1.0.beta7 of the beta and tests-passed branches, a malicious user can edit a post in a topic and cause a DoS with a carefully crafted edit reason. The issue is patched in version 3.0.6 of the stable branch and version 3.1.0.beta7 of the beta and tests-passed branches. There are no known workarounds for this vulnerability.

Discourse is an open source discussion platform. Prior to version 3.0.6 of the stable branch and version 3.1.0.beta7 of the beta and tests-passed branches, more users than permitted could be created from invite links. The issue is patched in version 3.0.6 of the stable branch and version 3.1.0.beta7 of the beta and tests-passed branches. As a workaround, use restrict to email address invites.

Discourse is an open source discussion platform. Prior to version 3.1.0.beta7 of the beta and tests-passed branches, a CSP (Content Security Policy) nonce reuse vulnerability was discovered could allow cross-site scripting (XSS) attacks to bypass CSP protection for anonymous (i.e. unauthenticated) users. There are no known XSS vectors at the moment, but should one be discovered, this vulnerability would allow the XSS attack to bypass CSP and execute successfully. This vulnerability isn't applicable to logged-in users. Version 3.1.0.beta7 contains a patch. The stable branch doesn't have this vulnerability. A workaround to prevent the vulnerability is to disable Google Tag Manager, i.e., unset the gtm container id setting.

Discourse is an open source discussion platform. Prior to version 3.0.4 of the stable branch and version 3.1.0.beta5 of the beta and tests-passed branches, multiple duplicate topics could be created if topic embedding is enabled. This issue is patched in version 3.0.4 of the stable branch and version 3.1.0.beta5 of the beta and tests-passed branches. As a workaround, disable topic embedding if it has been enabled.

Discourse is an open source discussion platform. Prior to version 3.0.4 of the stable branch and version 3.1.0.beta5 of the beta and tests-passed branches, the lack of restrictions on the iFrame tag makes it easy for an attacker to exploit the vulnerability and hide subsequent comments from other users. This issue is patched in version 3.0.4 of the stable branch and version 3.1.0.beta5 of the beta and tests-passed branches. There are no known workarounds.

Discourse is an open source discussion platform. Prior to version 3.0.4 of the stable branch and version 3.1.0.beta5 of the beta and tests-passed branches, if a site has modified their general category permissions, they could be set back to the default. This issue is patched in version 3.0.4 of the stable branch and version 3.1.0.beta5 of the beta and tests-passed branches. A workaround, only if you are modifying the general category permissions, is to use a new category for the same purpose.

Discourse is an open source platform for community discussion. In affected versions a user logged as an administrator can call arbitrary methods on the SiteSetting class, notably #clearcache! and #notifychanged!, which when done on a multisite instance, can affect the entire cluster resulting in a denial of service. Users not running in multisite environments are not affected. This issue is patched in the latest stable, beta and tests-passed versions of Discourse. Users are advised to upgrade. There are no known workarounds for this vulnerability.

Discourse is an open source platform for community discussion. Due to the improper sanitization of SVG files, an attacker can execute arbitrary JavaScript on the users’ browsers by uploading a crafted SVG file. This issue is patched in the latest stable and tests-passed versions of Discourse. Users are advised to upgrade. For users unable to upgrade there are two possible workarounds: enable CDN handing of uploads (and ensure the CDN sanitizes SVG files) or disable SVG file uploads by ensuring that the authorized extensions site setting does not include svg (or reset that setting to the default, by default Discourse doesn't enable SVG uploads by users).

Discourse is an open source platform for community discussion. This vulnerability is not exploitable on the default install of Discourse. A custom feature must be enabled for it to work at all, and the attacker’s payload must pass the CSP to be executed. However, if an attacker succeeds in embedding Javascript that does pass the CSP, it could result in session hijacking for any users that view the attacker’s post. The vulnerability is patched in the latest tests-passed, beta and stable branches. Users are advised to upgrade. Users unable to upgrade should enable and/or restore your site's CSP to the default one provided with Discourse. Remove any embed-able hosts configured.

Discourse is an open source platform for community discussion. In affected versions a maliciously crafted request from a Discourse administrator can lead to a long-running request and eventual timeout. This has the greatest potential impact in shared hosting environments where admins are untrusted. This issue has been addressed in versions 3.0.3 and 3.1.0.beta4. Users are advised to upgrade. There are no known workarounds for this vulnerability.

Discourse is an open-source discussion platform. Prior to version 3.1.0.beta3 of the beta and tests-passed branches, some user provided URLs were being passed to FastImage without SSRF protection. Insufficient protections could enable attackers to trigger outbound network connections from the Discourse server to private IP addresses. This affects any site running the tests-passed or beta branches versions 3.1.0.beta2 and prior. This issue is patched in version 3.1.0.beta3 of the beta and tests-passed branches. There are no known workarounds.

Discourse is an open-source discussion platform. Prior to version 3.1.0.beta3 of the beta and tests-passed branches, attackers are able to bypass Discourse's server-side request forgery (SSRF) protection for private IPv4 addresses by using a IPv4-mapped IPv6 address. The issue is patched in the latest beta and tests-passed version of Discourse. version 3.1.0.beta3 of the beta and tests-passed branches. There are no known workarounds.

Discourse is an open-source discussion platform. Prior to version 3.0.2 of the stable branch and version 3.1.0.beta3 of the beta and tests-passed branches, a user logged as an administrator can request backups multiple times, which will eat up all the connections to the DB. If this is done on a site using multisite, then it can affect the whole cluster. The vulnerability is patched in version 3.0.2 of the stable branch and version 3.1.0.beta3 of the beta and tests-passed branches. There are no known workarounds.

Discourse is an open-source discussion platform. Prior to version 3.0.1 of the stable branch and version 3.1.0.beta2 of the beta and tests-passed branches, a maliciously crafted URL can be included in a user's full name field to to carry out cross-site scripting attacks on sites with a disabled or overly permissive CSP (Content Security Policy). Discourse's default CSP prevents this vulnerability. The vulnerability is patched in version 3.0.1 of the stable branch and version 3.1.0.beta2 of the beta and tests-passed branches. As a workaround, enable and/or restore your site's CSP to the default one provided with Discourse.

Discourse is an open-source messaging platform. In versions 3.0.1 and prior on the stable branch and versions 3.1.0.beta2 and prior on the beta and tests-passed branches, the count of personal messages displayed for a tag is a count of all personal messages regardless of whether the personal message is visible to a given user. As a result, any users can technically poll a sensitive tag to determine if a new personal message is created even if the user does not have access to the personal message.

In the patched versions, the count of personal messages tagged with a given tag is hidden by default. To revert to the old behaviour of displaying the count of personal messages for a given tag, an admin may enable the displaypersonalmessagestagcounts site setting.

Discourse is an open source platform for community discussion. Tags that are normally private are showing in metadata. This affects any site running the tests-passed or beta branches >= 3.1.0.beta2. The issue is patched in the latest beta and tests-passed version of Discourse.

Discourse is an open source discussion platform. In affected versions a malicious user can cause a regular expression denial of service using a carefully crafted git URL. This issue is patched in the latest stable, beta and tests-passed versions of Discourse. Users are advised to upgrade. There are no known workarounds for this issue.

Discourse is an open source discussion platform. The embeddable comments can be exploited to create new topics as any user but without any clear title or content. This issue is patched in the latest stable, beta and tests-passed versions of Discourse. As a workaround, disable embeddable comments by deleting all embeddable hosts.

Discourse is an open-source discussion platform. Prior to version 3.0.1 on the stable branch and version 3.1.0.beta2 on the beta and tests-passed branches, someone can use the excludetag param to filter out topics and deduce which ones were using a specific hidden tag. This affects any Discourse site using hidden tags in public categories. This issue is patched in version 3.0.1 on the stable branch and version 3.1.0.beta2 on the beta and tests-passed branches. As a workaround, secure any categories that are using hidden tags, change any existing hidden tags to not include private data, or remove any hidden tags currently in use.

Discourse is an open-source discussion platform. Prior to version 3.0.1 on the stable branch and version 3.1.0.beta2 on the beta and tests-passed branches, a malicious user can cause a regular expression denial of service using a carefully crafted user agent. This issue is patched in version 3.0.1 on the stable branch and version 3.1.0.beta2 on the beta and tests-passed branches. There are no known workarounds.

Discourse is an open-source discussion platform. Prior to version 3.0.1 on the stable branch and 3.1.0.beta2 on the beta and tests-passed branches, when submitting a membership request, there is no character limit for the reason provided with the request. This could potentially allow a user to flood the database with a large amount of data. However it is unlikely this could be used as part of a DoS attack, as the paths reading back the reasons are only available to administrators. Starting in version 3.0.1 on the stable branch and 3.1.0.beta2 on the beta and tests-passed branches, a limit of 280 characters has been introduced for membership requests.

Discourse is an open-source discussion platform. Prior to version 3.0.1 on the stable branch and 3.1.0.beta2 on the beta and tests-passed branches, the contents of latest/top routes for restricted tags can be accessed by unauthorized users. This issue is patched in version 3.0.1 on the stable branch and 3.1.0.beta2 on the beta and tests-passed branches. There are no known workarounds.