Discourse is an open source platform for community discussion. In affected versions maliciously crafted requests could lead to remote code execution. This resulted from a lack of validation in subscribeurl values. This issue is patched in the latest stable, beta and tests-passed versions of Discourse. To workaround the issue without updating, requests with a path starting /webhooks/aws path could be blocked at an upstream proxy.

discourse-bbcode is the official BBCode plugin for Discourse. Prior to commit 91478f5, CSS injection can occur when rendering content generated with the discourse-bccode plugin. This vulnerability only affects sites which have the discourse-bbcode plugin installed and enabled. This issue is patched in commit 91478f5. As a workaround, ensure that the Content Security Policy is enabled and monitor any posts that contain bbcode.

Discourse is an open source platform for community discussion. Prior to version 3.1.3 of the stable branch and version 3.2.0.beta3 of the beta and tests-passed branches, the embedding feature is susceptible to server side request forgery. The issue is patched in version 3.1.3 of the stable branch and version 3.2.0.beta3 of the beta and tests-passed branches. As a workaround, disable the Embedding feature.

Discourse is an open source platform for community discussion. Sites that are using discourse connect but still have local logins enabled could allow attackers to bypass discourse connect to create accounts and login. This problem is patched in the latest version of Discourse. Users unable to upgrade who are using discourse connect may disable all other login methods as a workaround.

Discourse AI is a Discourse plugin which provides a number of AI features. When sharing Discourse AI Bot conversations into posts, if the conversation had HTML entities those could leak into the Discourse application when a user visited a post with a onebox to said conversation. This issue has been addressed in commit 92f122c. Users are advised to update. Users unable to update may remove all groups from ai bot public sharing allowed groups site setting.

Discourse is an open source discussion platform. In versions prior to 2.8.9 on the stable branch and prior to 2.9.0.beta10 on the beta and tests-passed branches, admins can upload a maliciously crafted Zip or Gzip Tar archive to write files at arbitrary locations and trigger remote code execution. The problem is patched in version 2.8.9 on the stable branch and version 2.9.0.beta10 on the beta and tests-passed branches. There are no known workarounds.

Discourse is a platform for community discussion. Users who receive an invitation link that is not scoped to a single email address can enter any non-admin user's email and gain access to their account when accepting the invitation. All users should upgrade to the latest version. A workaround is temporarily disabling invitations with SiteSetting.maxinvitesperday = 0 or scope them to individual email addresses.

Discourse is an open source discussion platform. Versions prior to 2.7.13 in stable, 2.8.0.beta11 in beta, and 2.8.0.beta11 in tests-passed allow some users to log in to a community before they should be able to do so. A user invited via email to a forum with mustapproveusers enabled is going to be automatically logged in, bypassing the check that does not allow unapproved users to sign in. They will be able to do everything an approved user can do. If they logout, they cannot log back in. This issue is patched in the stable version 2.7.13, beta version 2.8.0.beta11, and tests-passed version 2.8.0.beta11. One may disable invites as a workaround. Administrators can increase mintrustleveltoallowinvite to reduce the attack surface to more trusted users.

Discourse is an open source platform for community discussion. Versions prior to 2.8.13 (stable), 3.0.0.beta16 (beta) and 3.0.0beta16 (tests-passed), are vulnerable to cross-site Scripting. A maliciously crafted URL can be included in a post to carry out cross-site scripting attacks on sites with disabled or overly permissive CSP (Content Security Policy). Discourse's default CSP prevents this vulnerability. This vulnerability is patched in versions 2.8.13 (stable), 3.0.0.beta16 (beta) and 3.0.0beta16 (tests-passed). As a workaround, enable and/or restore your site's CSP to the default one provided with Discourse.

Discourse is a platform for community discussion. The message serializer uses the full list of expanded chat mentions (@all and @here) which can lead to a very long array of users. This issue was patched in versions 3.1.4 and beta 3.2.0.beta5.

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 platform for community discussion. An attacker can make several XHR requests until the cache is poisoned with a response without any preloaded data. This issue only affects anonymous visitors of the site. This problem has been patched in the latest version of Discourse. Users are advised to upgrade. Users unable to upgrade should disable anonymous cache by setting the DISCOURSEDISABLEANONCACHE environment variable to a non-empty value.

Discourse is an open source platform for community discussion. In affected versions an attacker can make craft an XHR request to poison the anonymous cache (for example, the cache may have a response with missing preloaded data). This issue only affects anonymous visitors of the site. This problem has been patched in the latest version of Discourse. Users are advised to upgrade. Users unable to upgrade should disable anonymous cache by setting the DISCOURSEDISABLEANONCACHE environment variable to a non-empty value.

Discourse is an open source platform for community discussion. In affected versions an attacker can carefully craft a request with the right request headers to poison the anonymous cache (for example, the cache may have a response with missing preloaded data). This issue only affects anonymous visitors of the site. This problem has been patched in the latest version of Discourse. Users are advised to upgrade. Users unable to upgrade may disable anonymous cache by setting the DISCOURSEDISABLEANONCACHE environment variable to a non-empty value.

Discourse is an open-source discussion platform. In Discourse versions 2.7.5 and prior, parsing and rendering of YouTube Oneboxes can be susceptible to XSS attacks. This vulnerability only affects sites which have modified or disabled Discourse's default Content Security Policy. The issue is patched in stable version 2.7.6, beta version 2.8.0.beta3, and tests-passed version 2.8.0.beta3. As a workaround, ensure that the Content Security Policy is enabled, and has not been modified in a way which would make it more vulnerable to XSS attacks.

Discourse is an option source discussion platform. Prior to version 2.8.14 on the stable branch and version 3.0.0.beta16 on the beta and tests-passed branches, when a user requests for a password reset link email, then changes their primary email, the old reset email is still valid. When the old reset email is used to reset the password, the Discourse account's primary email would be re-linked to the old email. If the old email address is compromised or has transferred ownership, this leads to an account takeover. This is however mitigated by the SiteSetting emailtokenvalidhours which is currently 48 hours. Users should upgrade to versions 2.8.14 or 3.0.0.beta15 to receive a patch. As a workaround, lower emailtokenvalidhours as needed.

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 platform for community discussion. Improper escaping of user input allowed for Cross-site Scripting attacks via the digest email preview UI. This issue only affects sites with CSP disabled. This issue has been patched in the 3.1.1 stable release as well as the 3.2.0.beta1 release. Users are advised to upgrade. Users unable to upgrade should ensure CSP is enabled on the forum.

Discourse is an option source discussion platform. Prior to version 2.8.14 on the stable branch and version 3.0.0.beta16 on the beta and tests-passed branches, pending post titles can be used for cross-site scripting attacks. Pending posts can be created by unprivileged users when a category has the "require moderator approval of all new topics" setting set. This vulnerability can lead to a full XSS on sites which have modified or disabled Discourse’s default Content Security Policy. A patch is available in versions 2.8.14 and 3.0.0.beta16.

Discourse is a platform for community discussion. A malicious admin could use this vulnerability to perform port enumeration on the local host or other hosts on the internal network, as well as against hosts on the Internet. Latest stable, beta, and test-passed versions are now patched. As a workaround, self-hosters can use DISCOURSEBLOCKEDIPBLOCKS env var (which overrides blockedipblocks setting) to stop webhooks from accessing private IPs.

Discourse is an open source platform for community discussion. Without a rate limit on the POST /uploads endpoint, it makes it easier for an attacker to carry out a DoS attack on the server since creating an upload can be a resource intensive process. Do note that the impact varies from site to site as various site settings like maximagesizekb, maxattachmentsizekb and maximagemegapixels will determine the amount of resources used when creating an upload. The issue is patched in the latest stable, beta and tests-passed version of Discourse. Users are advised to upgrade. Users unable to upgrade should reduce maximagesizekb, maxattachmentsizekb and maximagemegapixels as smaller uploads require less resources to process. Alternatively, clientmaxbodysize can be reduced in Nginx to prevent large uploads from reaching the server.

Discourse is an open source platform for community discussion. In affected versions an attacker can learn that secret categories exist when they have backgrounds set. The issue is patched in the latest stable, beta and tests-passed version of Discourse. Users are advised to upgrade. Users unable to upgrade should temporarily remove category backgrounds.

Discourse is an open-source discussion platform. Prior to version 3.2.3 on the stable branch and version 3.3.0.beta3 on the tests-passed branch, Oneboxing against a carefully crafted malicious URL can reduce the availability of a Discourse instance. The problem has been patched in version 3.2.3 on the stable branch and version 3.3.0.beta3 on the tests-passed branch. There are no known workarounds available for this vulnerability.

Discourse is an open source discussion platform. Prior to 3.2.5 and 3.3.0.beta5, crafting requests to submit very long tag group names can reduce the availability of a Discourse instance. This vulnerability is fixed in 3.2.5 and 3.3.0.beta5.

Discourse is an open source platform for community discussion. This vulnerability only impacts Discourse instances configured to use FileStore::LocalStore which means uploads and backups are stored locally on disk. If an attacker knows the name of the Discourse backup file, the attacker can trick nginx into sending the Discourse backup file with a well crafted request. This issue is patched in the latest stable, beta and tests-passed versions of Discourse. Users are advised to upgrade. Users unable to upgrade can either 1. Download all local backups on to another storage device, disable the enablebackups site setting and delete all backups until the site has been upgraded to pull in the fix. Or 2. Change the backuplocation site setting to s3 so that backups are stored and downloaded directly from S3.

Discourse is an open-source community platform. A data leak vulnerability affects sites deployed between commits 10df7fdee060d44accdee7679d66d778d1136510 and 82d84af6b0efbd9fa2aeec3e91ce7be1a768511b. On login-required sites, the leak meant that some content on the site's homepage could be visible to unauthenticated users. Only login-required sites that got deployed during this timeframe are affected, roughly between April 30 2025 noon EDT and May 2 2025, noon EDT. Sites on the stable branch are unaffected. Private content on an instance's homepage could be visible to unauthenticated users on login-required sites. Versions of 3.5.0.beta4 after commit 82d84af6b0efbd9fa2aeec3e91ce7be1a768511b are not vulnerable to the issue. No workarounds are available. Sites must upgrade to a non-vulnerable version of Discourse.

Discourse is an open source discussion platform. Prior to versions 2025.12.2, 2026.1.1, and 2026.2.0, an IDOR vulnerability in the directory items endpoint allows any user, including anonymous users, to retrieve private user field values for all users in the directory. The userfieldids parameter in DirectoryItemsController#index accepts arbitrary user field IDs without authorization checks, bypassing the visibility restrictions (showonprofile / showonusercard) that are enforced elsewhere (e.g., UserCardSerializer via Guardian#alloweduserfieldids). An attacker can request GET /directoryitems.json?period=all&userfieldids=<id> with any private field ID and receive that field's value for every user in the directory response. This enables bulk exfiltration of private user data such as phone numbers, addresses, or other sensitive custom fields that admins have explicitly configured as non-public. The issue is patched in versions 2025.12.2, 2026.1.1, and 2026.2.0 by filtering userfieldids against UserField.publicfields for non-staff users before building the custom field map. As a workaround, site administrators can remove sensitive data from private user fields, or disable the user directory via the enableuserdirectory site setting.

Discourse is an open source platform for community discussion. New chat messages can be read by making an unauthenticated POST request to MessageBus. This issue is patched in the 3.1.1 stable and 3.2.0.beta2 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. A malicious request can cause production log files to quickly fill up and thus result in the server running out of disk space. This problem has been patched in the 3.1.1 stable and 3.2.0.beta2 versions of Discourse. It is possible to temporarily work around this problem by reducing the clientmaxbodysize nginx directive. clientmaxbodysize will limit the size of uploads that can be uploaded directly to the server.

Discourse before 2.3.0 and 2.4.x before 2.4.0.beta3 lacks a confirmation screen when logging in via an email link.