Vendor
Discourse
323 known vulnerabilities.
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Medium 6.1
Discourse < 1.9.0.beta13 Reflected XSS via /email/unsubscribed
Discourse 1.9.0.beta2 before 1.9.0.beta13 contains a reflected cross-site scripting vulnerability that allows unauthenticated attackers to inject scripts through the email parameter of /email/unsubscribed. Attackers can craft GET requests with SVG onload payl…
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Medium 4.3
Discourse Doc Categories: Doc category index refresh leaks private topic titles
Discourse Doc Categories is a plugin for organizing Discourse topics as documentation. Prior to the verified source fix, the doc category index refresh resolves linked titles for private messages or restricted category topics without enforcing the viewer's au…
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Medium 6.4
Discourse: Encode action_code_who in mention URLs
Discourse is an open-source discussion platform. Prior to 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0, the topic small-action and nested-activity-log components interpolated the free-form action_code_who value into mention-link href attributes without URL enco…
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Medium 5.0
Discourse: Chat upload filenames rendered as raw HTML in excerpts
Discourse is an open-source discussion platform. Prior to 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0, attacker-controlled upload filenames used in chat message excerpts were rendered as unescaped HTML. A user able to upload a file and send chat content could …
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Medium 5.4
Discourse: Stored HTML injection in video notification emails
Discourse is an open-source discussion platform. Prior to 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0, provider-controlled video titles in lazy video embeds could be reparsed as HTML when Discourse generated notification emails or chat summaries. A user with s…
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Medium 4.3
Discourse: Wildcard iframe origin allowlist bypass via authority separators
Discourse is an open-source discussion platform. Prior to 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0, sites using wildcard patterns in the allowed_iframes setting could accept a crafted iframe URL whose allowlisted suffix appeared after a URL authority separa…
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Medium 6.5
Discourse: Escape LIKE metacharacters in upload paths to prevent disclosure
Discourse is an open-source discussion platform. Prior to 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0, authenticated users could supply unescaped SQL LIKE metacharacters to upload-resolution patterns, causing wildcard input to select unrelated upload records i…
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Medium 5.4
Discourse: Block post iframes whose encoded userinfo bypasses the allowed_iframes allowlist
Discourse is an open-source discussion platform. Prior to 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0, the Discourse post sanitizer allowed a stored cross-origin iframe to bypass the allowed_iframes prefix policy when the iframe src contained encoded userinfo.…
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Medium 4.2
Discourse: Non-participant moderators can read, edit, and delete PM content through Discourse AI reviewables
Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, Discourse AI reviewables associated with private messages could appear in the moderator review queue of a moderator who was not a participant in the message.…
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Medium 5.4
Discourse: Stored XSS via unescaped actor name in post actions
Discourse is an open-source discussion platform. Prior to 2026.7.0, the post action component failed to escape user-controlled display names before interpolating them into an HTML string passed to trustHTML. A user who could choose a crafted display name coul…
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Medium 5.3
Discourse: Hidden first-post excerpt is emitted in Q&A schema JSON-LD
Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, hidden or otherwise unviewable first-post content was leaked as an excerpt in the publicly-served Q&A (QAPage) JSON-LD structured data, exposing it to any un…
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Medium 4.3
Discourse: Shared-draft titles and excerpts leak through group post serialization
Discourse is an open-source discussion platform. Prior o 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, users who were allowed to view a group’s activity, but were not permitted to see shared drafts, could still receive shared-draft entries through the group pos…
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Medium 4.3
Discourse: Review queue exposes flag-related private message excerpts to category group moderators
Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.1, on sites with category group moderation enabled, the review queue could include an excerpt (and permalink) of the private message attached to a flag, even wh…
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Medium 4.3
Discourse: Templates endpoint exposes hidden tag names
Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, the discourse_templates endpoint exposed hidden tag names because DiscourseTemplates::TemplatesSerializer in plugins/discourse-templates/app/serializers/disc…
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Medium 6.3
Discourse: Onebox iframe origin allowlist enforces URL authority boundary
Discourse is an open-source discussion platform. Prior to 2026.1.7, an authenticated user could submit specially formed URLs that bypassed the Onebox allowlist and embedded malicious content in a site. This issue is fixed in versions 2026.1.7, 2026.6.2, 2026.…
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Medium 4.8
Discourse: Stored XSS in the moderation review queue
Discourse is an open-source discussion platform. Prior to 026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, a low-privileged user could place crafted content in the moderation review queue that executed stored cross-site scripting when a moderator viewed it on a sit…
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Medium 6.5
Discourse: Unauthorized eavesdropping on private AI bot conversations.
Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, an authenticated user could eavesdrop on private AI bot conversations through the AI bot reply stream. The issue is fixed in 2026.1.6, 2026.5.2, 2026.6.1, an…
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Medium 5.4
Discourse: Stored XSS in staff action logs injects staff UI
Discourse is an open-source discussion platform. Prior to 2026.1.6, the staff action log model rendered unescaped previous and new value fields that could inject stored cross-site scripting into the staff interface. The issue is fixed in 2026.1.6, 2026.5.2, 2…
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Medium 4.3
Discourse: Private Chat Threat Message Disclosure via Chat Onebox Channel/Threat ID Mismatch
Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, plugins/chat/lib/chat/onebox_handler.rb resolves Chat::Thread by route thread_id independently of the route channel_id before checking whether the user can p…
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Medium 5.3
Discourse: Anonymous sidebar serialization exposes descriptions of category-restricted tags
Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, SiteSerializer.anonymous_default_navigation_menu_tags serializes tags from SiteSetting.default_navigation_menu_tags without applying DiscourseTagging.filter_…
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Medium 4.3
Discourse: Duplicate lookup reveals restricted topic titles through canonicalized URLs
Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, TopicLink.extract_from, TopicLink.ensure_entry_for, and TopicLink.duplicate_lookup do not consistently enforce Guardian.can_see? checks when processing inter…
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Medium 5.3
Discourse: Onebox Domain Blocklist Bypass via Case-Sensitive Comparison
Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, Onebox::DomainChecker.is_blocked? compares hostnames and SiteSetting.blocked_onebox_domains entries case-sensitively, allowing an attacker to bypass configur…
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Medium 6.4
Discourse: HTML injection in PrettyText.format_for_email from cooked-attribute reparsing
Discourse is an open-source discussion platform. Prior to 2026.1.7, 2026.6.2, 2026.7.1, and 2026.8.0-latest.1, Discourse has HTML injection in PrettyText.format_for_email because cooked attribute values are reparsed as markup. Crafted Vimeo iframe sources, se…
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Medium 5.3
Discourse: Private event sample invitees are serialized to non-invited event viewers
Discourse is an open-source discussion platform. Prior to 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5, EventSerializer could expose invited group names, sample invitees, and attendance statistics to users who could view the topic but were not entitled to view …
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Medium 5.3
Discourse: Hidden post revisions leak through adjacent visible diffs
Discourse is an open-source discussion platform. Prior to 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5, post revisions that should be hidden from regular users could be leaked through visible diffs on adjacent revisions serialized by PostRevisionSerializer. Thi…
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Medium 5.4
Discourse: Insufficient SVG sanitization logic
Discourse is an open-source discussion platform. Prior to 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5, insufficient SVG sanitization in upload and user avatar handling could lead to cross-site scripting when a user visited specific URLs that are not normally p…
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Medium 6.3
Discourse: Secure uploads exposed by hotlinked image copying
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 i…
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Medium 6.3
Discourse: Hidden tag names leaked via category serializers
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 anonymo…
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Medium 6.5
Discourse: Regular users can route multipart uploads into the admin backup store
Discourse is an open-source discussion platform. Prior to 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5, regular users could route direct S3 multipart uploads through ExternalUploadManager into the admin backup store. This issue is fixed in versions 2026.6.0, 20…
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Medium 6.5
Discourse: Forged AWS SNS bounce notifications can disable a targeted user's email (missing TopicArn binding)
Discourse is an open-source discussion platform. Prior to 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5, the AWS SES bounce webhook at POST /webhooks/aws verified that SNS messages were signed by Amazon but did not bind them to trusted TopicArn values, allowing …
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Medium 5.3
Discourse: Don't leak restricted tag group names via tag info
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, DetailedTagSerializer#tag_group_names returned every tag group a tag belonged to wit…
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Medium 4.3
Discourse: Prevent webhook payload disclosure on event redelivery
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, the MessageBus.publish call for /web_hook_events/<id> in Jobs::RedeliverWebHookEvent…
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Medium 6.8
Discourse: Cross-site backup access via path traversal in multisite local backups
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, a path traversal vulnerability in Discourse backup handling could allow an authentic…
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Medium 5.3
Discourse: Chat misauthorization and information disclosure
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, four authorization/disclosure issues in the chat plugin (one also involving discours…
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Medium 4.3
Discourse: Hidden reply-to post raw can be disclosed through AI explain prompts
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, the AI "explain" helper only checks can_see? on the post being explained, not its re…
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Medium 6.5
Discourse: Non-staff group owners can see email password in plaintext through group history
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, group owners who are not necessarily admins or moderators can view a group's outgoin…
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Medium 5.4
Discourse: Replying to a whisper lets non-whisperers create staff-only whisper posts
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, a flaw in how replies to whisper posts are handled allows authenticated users outsid…
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Medium 4.3
Discourse: GroupPostSerializer leaks hidden full names through reaction post association
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, GroupPostSerializer declared include_user_long_name? as the predicate for its :name …
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Medium 4.3
Discourse: Category queue reviewers can read raw incoming emails from queued posts
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, ReviewableQueuedPostSerializer unconditionally included payload["raw_email"] for pos…
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Medium 4.3
Discourse: Bot debug endpoints disclose whisper translation audit logs
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, bot debug endpoints disclose whisper translation audit logs. This issue has been pat…