BIT-DISCOURSE-2026-72728 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, 2026.7.1, and 2026.8.0...

BIT-DISCOURSE-2026-72727 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 site with a modified or disabled default...

BIT-DISCOURSE-2026-72726 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, and 2026.7.0...

BIT-DISCOURSE-2026-72725 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, 2026.6.1, and 2026.7.0...

BIT-DISCOURSE-2026-72724 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/oneboxhandler.rb resolves Chat::Thread by route threadid independently of the route channelid before checking whether the user can preview the selected chat channel. An...

BIT-DISCOURSE-2026-72723 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.anonymousdefaultnavigationmenutags serializes tags from SiteSetting.defaultnavigationmenutags without applying DiscourseTagging.filtervisible for the anonymous viewer. An...

BIT-DISCOURSE-2026-72722 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.extractfrom, TopicLink.ensureentryfor, and TopicLink.duplicatelookup do not consistently enforce Guardian.cansee? checks when processing internal links. An authenticated user can submit...

BIT-DISCOURSE-2026-72721 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.isblocked? compares hostnames and SiteSetting.blockedoneboxdomains entries case-sensitively, allowing an attacker to bypass configured Onebox domain restrictions by changing...

BIT-DISCOURSE-2026-72720 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, Discourse has HTML injection in PrettyText.formatforemail because cooked attribute values are reparsed as markup. Crafted Vimeo iframe sources, secure-upload URLs or dimensions, and hashtag...

PT-2026-73254

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 site with a modified or disabled default...

PT-2026-73252

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, 2026.6.1, and 2026.7.0...

PT-2026-73259

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/discourse templates/templates serializer.r...

PT-2026-73248

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 configured Onebox domain restrictions by...

PT-2026-76682

Name of the Vulnerable Software and Affected Versions Discourse versions prior to 2026.1.6 Discourse versions prior to 2026.5.2 Discourse versions prior to 2026.6.1 Discourse versions prior to 2026.7.0 Description Users permitted to view group activity but restricted from seeing shared drafts can...

PT-2026-73256

Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, the discourse-local-dates plugin rendered crafted local-date format data as HTML on sites with a modified or disabled default Content Security Policy. This issue is fixed in versions 2026.1.6,...

PT-2026-76680

Name of the Vulnerable Software and Affected Versions Discourse versions prior to 2026.1.6 Discourse versions prior to 2026.5.2 Discourse versions prior to 2026.6.1 Discourse versions prior to 2026.7.0 Description Hidden or unviewable first-post content is leaked as an excerpt within the...

CVE-2026-59829: Missing Authorization

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 when the reviewing category moderator was...

CVE-2026-55674: 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 colorschemeid or darkschemeid cookie to inject arbitrary HTML into a Discourse page. Because the cookie value was rendered...

PT-2026-73251

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 preview the selected chat channel. An...

PT-2026-73247

Discourse is an open-source discussion platform. Prior to 2026.1.7, 2026.6.2, 2026.7.1, and 2026.8.0, Discourse has HTML injection in PrettyText.format for email because cooked attribute values are reparsed as markup. Crafted Vimeo iframe sources, secure-upload URLs or dimensions, and hashtag...