Zulip Zulip Server any version

In Zulip Server versions from 1.7.0 to before 2.0.7, a bug in the new user signup process meant that users who registered their account using social authentication (e.g., GitHub or Google SSO) in an organization that also allows password authentication could have their personal API key stolen by an unprivileged attacker, allowing nearly full access to the user's account.

Multi-use invitations can grant access to other organizations in Zulip

Zulip Server 2.x before 2.1.7 allows eval injection if a privileged attacker were able to write directly to the postgres database, and chose to write a crafted custom profile field value.

In Zulip Server before 1.7.1, on a server with multiple realms, a vulnerability in the invitation system lets an authorized user of one realm on the server create a user account on any other realm.

Zulip Authentication Backend Configuration Bypass

Zulip Server before 2.1.5 has Incorrect Access Control because 0198_preregistrationuser_invited_as adds the administrator role to invitations.

Zulip from 8.0 to 8.3 contains a memory leak vulnerability in the handling of popovers.

/api/v1/jwt/fetch_api_key endpoint can leak if an email address has an account in Zulip server

Zulip XSS in digest preview URL

The Markdown parser in Zulip server before 2.0.5 used a regular expression vulnerable to exponential backtracking. A user who is logged into the server could send a crafted message causing the server to spend an effectively arbitrary amount of CPU time and stall the processing of future messages.

Moving single messages from public to private streams leaves them accessible

Zulip vulnerable to insufficient authorization check for edition/deletion of messages and topics in private streams by former subscribers

The image thumbnailing handler in Zulip Server versions 1.9.0 to before 2.0.8 allowed an open redirect that was visible to logged-in users.

In Zulip Server versions before 1.7.2, there was an XSS issue with stream names in topic typeahead.

In Zulip Server versions 1.5.x, 1.6.x, and 1.7.x before 1.7.2, there was an XSS issue with muting notifications.

In Zulip Server versions before 1.7.2, there were XSS issues with the frontend markdown processor.

Zulip Server before 2.1.5 allows reflected XSS via the Dropbox webhook.

Zulip Server before 2.1.3 allows reverse tabnabbing via the Markdown functionality.

Zulip Server before 2.1.3 allows XSS via the modal_link feature in the Markdown functionality.

Zulip Server before 2.1.5 allows reverse tabnapping via a topic header link.

In Zulip Server versions before 1.7.2, there was an XSS issue with user uploads and the (default) LOCAL_UPLOADS_DIR storage backend.

Zulip Server before 2.1.3 allows XSS via a Markdown link, with resultant account takeover.

Zulip server before 2.0.5 incompletely validated the MIME types of uploaded files. A user who is logged into the server could upload files of certain types to mount a stored cross-site scripting attack on other logged-in users. On a Zulip server using the default local uploads backend, the attack is only effective against browsers lacking support for Content-Security-Policy such as Internet Explorer 11. On a Zulip server using the S3 uploads backend, the attack is confined to the origin of the configured S3 uploads hostname and cannot reach the Zulip server itself.

Cross-site scripting vulnerability in Zulip Server

Zulip affected by Stored XSS in user profile modal

An issue was discovered in Zulip Server before 3.4. A bug in the implementation of the all_public_streams API feature resulted in guest users being able to receive message traffic to public streams that should have been only accessible to members of the organization.

Zulip Server public data export contains attachments that are non-public

Zulip exports can leak private data

An error in the implementation of an autosubscribe feature in the check_stream_exists route of the Zulip group chat application server before 1.4.3 allowed an authenticated user to subscribe to a private stream that should have required an invitation from an existing member to join. The issue affects all previously released versions of the Zulip server.

An issue was discovered in Zulip Server before 3.4. A bug in the implementation of replies to messages sent by outgoing webhooks to private streams meant that an outgoing webhook bot could be used to send messages to private streams that the user was not intended to be able to send messages to.

An issue was discovered in Zulip Server before 3.4. A bug in the implementation of the can_forge_sender permission (previously is_api_super_user) resulted in users with this permission being able to send messages appearing as if sent by a system bot, including to other organizations hosted by the same Zulip installation.

Stream description leaks to ex-subscribers in Zulip

Zulip non-admins can invite new users to streams they would not otherwise be able to add existing users to

In the topic moving API in Zulip Server 3.x before 3.4, organization administrators were able to move messages to streams in other organizations hosted by the same Zulip installation.

Non-constant-time SCIM token comparison in Zulip Server

Zulip allows the deletion of Custom profile fields by administrators of a different organization