Discourse vulnerabilities
We track 57 vulnerabilities in Discourse products across 9 products. 57 are rated high or critical, and none are known to be exploited. The most recent was published on October 15, 2026.
Latest Discourse vulnerabilities
- 8.6 High severity
discourse-activity-pub: Insufficient Verification of Data Authenticity
Discourse ActivityPub adds ActivityPub support to Discourse. Prior to commit 1c8518b0f2abdf31cbea3e0b242f74d8994a9ba5, inbound ActivityPub processing does not sufficiently verify that the actor authenticated by the signed request matches the Activity actor and
- 7.7 High severity
discourse: Improper Neutralization of Input During Web Page Generation
Discourse is an open-source discussion platform. Prior to 2026.9.0, 2026.8.1, 2026.7.3, and 2026.1.9, oEmbed processing treated an entire attacker-controlled HTML fragment as trusted when the fragment contained an iframe whose source matched the configured all
- 7.5 High severity
discourse: Exposure of Sensitive Information to an Unauthorized Actor
Discourse is an open-source discussion platform. Prior to 2026.9.0, 2026.8.1, 2026.7.3, and 2026.1.9, sites with secure uploads enabled did not reconcile existing upload security metadata when a previously public category became read-restricted or when categor
- 7.5 High severity
discourse: Missing Authorization
Discourse is an open-source discussion platform. Prior to 2026.9.0, 2026.8.1, 2026.7.3, and 2026.1.9, MessageBus audience calculation could deliver messages from a read-restricted category chat channel to an authenticated user who could view the category but w
- 7.2 High severity
discourse: Improper Limitation of a Pathname to a Restricted Directory
Discourse is an open-source discussion platform. Prior to 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0, the iframe src traversal guard did not treat literal backslashes as path separators after decoded dot segments. A crafted source could therefore pass an allow
- 8.7 High severity
discourse: Improper Neutralization of Input During Web Page Generation
Discourse is an open-source discussion platform. Prior to 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0, the video placeholder component allowed crafted HTML to cause an attribute breakout and inject an attacker-controlled event handler. An authenticated user wit
- 9.3 Critical severity
discourse: Improper Neutralization of Input During Web Page Generation
Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, an unauthenticated attacker could send a single request with a crafted color_scheme_id (or dark_scheme_id) cookie to inject arbitrary HTML into a Discourse pa
- 7.1 High severity
discourse: Improper Neutralization of Special Elements used in an SQL Command
Discourse is an open-source discussion platform. From 2026.1.0-latest until 2026.1.7, 2026.6.2, 2026.7.1, and 2026.8.0-latest.1, anyone able to run a parameterized Data Explorer query, including non-staff members of a group a query is shared with, could craft
- 8.7 High severity
discourse: Improper Neutralization of Input During Web Page Generation
Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, the Rich Text Editor rendered a chat-transcript username as HTML, allowing stored cross-site scripting. This issue is fixed in versions 2026.1.6, 2026.5.2, 20
- 9.0 Critical severity
discourse: Improper Neutralization of Input During Web Page Generation
Discourse is an open-source discussion platform. Prior to 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5, a malicious second factor name on an attacker-controlled account was not escaped in the delete confirmation dialog, allowing stored cross-site scripting when
- 7.5 High severity
discourse: Exposure of Sensitive Information to an Unauthorized Actor
Discourse is an open-source discussion platform. Prior to 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5, restricted tag and tag-group names attached to publicly readable categories as allowed_tags, allowed_tag_groups, or required tag groups could leak to anonymou
- 7.5 High severity
discourse: Exposure of Sensitive Information to an Unauthorized Actor
Discourse is an open-source discussion platform. Prior to 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5, secure uploads could be exposed by pull_hotlinked_images when an attacker knew the secured upload URL and the secure_uploads site setting was enabled. This is
- 7.1 High severity
discourse: Improper Privilege Management
Discourse is an open-source discussion platform. Prior to 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5, the signup flow could allow newly registered users to set primary_group_id and gain whisper-group privileges without legitimate group membership on sites with
- 8.1 High severity
discourse: Improper Neutralization of Special Elements used in an OS Command
Discourse is an open-source discussion platform. Prior to 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5, under certain non-default configurations, processing of PDF uploads could be exploited to obtain RCE on the server. This issue is patched in 2026.6.0, 2026.5.
- 7.5 High severity
discourse: Exposure of Sensitive Information to an Unauthorized Actor
Discourse is an open-source discussion platform. From versions 2026.1.0-latest to before 2026.1.4, 2026.3.0-latest to before 2026.3.1, and 2026.4.0-latest to before 2026.4.1, chat events for public category channels are published to MessageBus without permissi
- 7.5 High severity
discourse: Missing Authorization
Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, an unauthenticated attacker can cause a legitimate Discourse authorization page to display an attacker-controlled domain, facilitating social engineer
- 8.2 High severity
Discourse is an open-source discussion platform.
Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, an authorization bypass in the poll plugin allowed authenticated users to vote on, remove votes from, or toggle the open/closed status of polls they d
- 7.5 High severity
discourse: Missing Authorization
Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, users who do not belong to the allowed policy creation groups can create functional policy acceptance widgets in posts under the right conditions. Ver
- 7.5 High severity
discourse: Insertion of Sensitive Information Into Sent Data
Discourse is an open-source discussion platform. Versions prior to 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 have a lack of visibility checks with a user action API endpoint that results in disclosure of the title and post excerpt to unauthorized users, leadin
- 7.5 High severity
discourse: Authorization Bypass Through User-Controlled Key
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 d
- 7.5 High severity
discourse: Authorization Bypass Through User-Controlled Key
Discourse is an open source discussion platform. Prior to versions 2025.12.2, 2026.1.1, and 2026.2.0, when the `patreon_webhook_secret` site setting is blank, an attacker can forge valid webhook signatures by computing an HMAC-MD5 with an empty string as the k
- 7.5 High severity
discourse: Exposure of Sensitive Information to an Unauthorized Actor
Discourse is an open source discussion platform. In versions prior to 3.5.4, 2025.11.2, 2025.12.1, and 2026.1.0, permalinks pointing to access-restricted resources (private topics, categories, posts, or hidden tags) were redirecting users to URLs containing th
- 9.9 Critical severity
discourse: Server-Side Request Forgery
Discourse is an open source discussion platform. In versions prior to 3.5.4, 2025.11.2, 2025.12.1, and 2026.1.0, a hostname validation issue in FinalDestination could allow bypassing SSRF protections under certain conditions. This issue is patched in versions
- 9.8 Critical severity
discourse: Session Fixation
Discourse is an open-source community discussion platform. Prior to version 3.4.7 on the `stable` branch and version 3.5.0.beta.8 on the `tests-passed` branch, upon issuing a physical security key for 2FA, the server generates a WebAuthn challenge, which the c
- 7.5 High severity
discourse: Exposure of Sensitive Information to an Unauthorized Actor
Discourse is an open-source discussion platform. The visibility of posts typed `whisper` is controlled via the `whispers_allowed_groups` site setting. Only users that belong to groups specified in the site setting are allowed to view posts typed `whisper`. How
- 9.8 Critical severity
discourse: Insecure Automated Optimizations
Discourse is an open-source discussion platform. Prior to version 3.4.4 of the `stable` branch, version 3.5.0.beta5 of the `beta` branch, and version 3.5.0.beta6-dev of the `tests-passed` branch, Codepen is present in the default `allowed_iframes` site setting
- 7.5 High severity
discourse: Uncontrolled Resource Consumption
Discourse is an open-source discussion platform. Prior to version 3.4.4 of the `stable` branch, version 3.5.0.beta5 of the `beta` branch, and version 3.5.0.beta6-dev of the `tests-passed` branch, sending a malicious URL in a PM to a bot user can cause a reduce
- 7.5 High severity
discourse: Exposure of Sensitive Information to an Unauthorized Actor
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
- 8.2 High severity
discourse: Origin Validation Error
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).
- 8.2 High severity
discourse: Origin Validation Error
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 anonym
- 9.0 Critical severity
discourse-ai: Improper Neutralization of Input During Web Page Generation
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
- 9.1 Critical severity
discourse: Exposure of Private Personal Information to an Unauthorized Actor
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 vers
- 8.2 High severity
discourse: Externally Controlled Reference to a Resource in Another Sphere
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 patch
- 8.2 High severity
discourse: Improper Authentication
Discourse is an open source platform for community discussion. A maliciously crafted email address could allow an attacker to bypass domain-based restrictions and gain access to private sites, categories and/or groups. This issue has been patched in the latest
- 7.5 High severity
discourse: Uncontrolled Resource Consumption
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.
- 7.5 High severity
Discourse is an open-source discussion platform.
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 pr
- 7.5 High severity
discourse: Exposure of Sensitive Information to an Unauthorized Actor
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
- 7.5 High severity
discourse: Uncontrolled Resource Consumption
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
- 7.2 High severity
discourse-ai: Server-Side Request Forgery
discourse-ai is the AI plugin for the open-source discussion platform Discourse. Prior to commit 94ba0dadc2cf38e8f81c3936974c167219878edd, interactions with different AI services are vulnerable to admin-initiated SSRF attacks. Versions of the plugin that inclu
- 8.1 High severity
discourse-microsoft-auth: Incorrect Authorization
`discourse-microsoft-auth` is a plugin that enables authentication via Microsoft. On sites with the `discourse-microsoft-auth` plugin enabled, an attack can potentially take control of a victim's Discourse account. Sites that have configured their application'