Zulip: Security Vulnerabilities
Zulip is an open-source team collaboration tool with unique topic-based threading. Zulip administrators can configure Zulip to limit who can add users to streams, and separately to limit who can invite users to the organization. In Zulip Server 6.1 and below, the UI which allows a user to invite a new user also allows them to set the streams that the new user is invited to -- even if the inviting user would not have permissions to add an existing user to streams. While such a configuration is likely rare in practice, the behavior does violate security-related controls. This does not let a user invite new users to streams they cannot see, or would not be able to add users to if they had that general permission. This issue has been addressed in version 6.2. Users are advised to upgrade. Users unable to upgrade may limit sending of invitations down to users who also have the permission to add users to streams.
CVSS Score
3.1
EPSS Score
0.006
Published
2023-05-19
Zulip is an open-source team collaboration tool. In versions of zulip prior to commit `2f6c5a8` but after commit `04cf68b` users could upload files with arbitrary `Content-Type` which would be served from the Zulip hostname with `Content-Disposition: inline` and no `Content-Security-Policy` header, allowing them to trick other users into executing arbitrary Javascript in the context of the Zulip application. Among other things, this enables session theft. Only deployments which use the S3 storage (not the local-disk storage) are affected, and only deployments which deployed commit 04cf68b45ebb5c03247a0d6453e35ffc175d55da, which has only been in `main`, not any numbered release. Users affected should upgrade from main again to deploy this fix. Switching from S3 storage to the local-disk storage would nominally mitigate this, but is likely more involved than upgrading to the latest `main` which addresses the issue.
CVSS Score
4.4
EPSS Score
0.005
Published
2023-02-07
Zulip is an open-source team collaboration tool. For organizations with System for Cross-domain Identity Management(SCIM) account management enabled, Zulip Server 5.0 through 5.6 checked the SCIM bearer token using a comparator that did not run in constant time. Therefore, it might theoretically be possible for an attacker to infer the value of the token by performing a sophisticated timing analysis on a large number of failing requests. If successful, this would allow the attacker to impersonate the SCIM client for its abilities to read and update user accounts in the Zulip organization. Organizations where SCIM account management has not been enabled are not affected.
CVSS Score
3.7
EPSS Score
0.005
Published
2022-11-16
Zulip is an open-source team collaboration tool with topic-based threading that combines email and chat. When displaying messages with embedded remote images, Zulip normally loads the image preview via a go-camo proxy server. However, an attacker who can send messages could include a crafted URL that tricks the server into embedding a remote image reference directly. This could allow the attacker to infer the viewer’s IP address and browser fingerprinting information. This vulnerability is fixed in Zulip Server 5.6. Zulip organizations with image and link previews [disabled](https://zulip.com/help/allow-image-link-previews) are not affected.
CVSS Score
4.3
EPSS Score
0.005
Published
2022-08-31
Zulip is an open source team chat and Zulip Mobile is an app for iOS and Andriod users. In Zulip Mobile through version 27.189, a crafted link in a message sent by an authenticated user could lead to credential disclosure if a user follows the link. A patch was released in version 27.190.
CVSS Score
8.0
EPSS Score
0.009
Published
2022-08-29
In zulip before 1.3.12, bot API keys were accessible to other users in the same realm.
CVSS Score
4.3
EPSS Score
0.004
Published
2022-07-28
In zulip before 1.3.12, deactivated users could access messages if SSO was enabled.
CVSS Score
7.5
EPSS Score
0.006
Published
2022-07-28
Zulip is an open source team chat tool. Due to an incorrect authorization check in Zulip Server 5.4 and earlier, a member of an organization could craft an API call that grants organization administrator privileges to one of their bots. The vulnerability is fixed in Zulip Server 5.5. Members who don’t own any bots, and lack permission to create them, can’t exploit the vulnerability. As a workaround for the vulnerability, an organization administrator can restrict the `Who can create bots` permission to administrators only, and change the ownership of existing bots.
CVSS Score
5.4
EPSS Score
0.006
Published
2022-07-22
Zulip is an open-source team collaboration tool. Zulip Server versions 2.1.0 above have a user interface tool, accessible only to server owners and server administrators, which provides a way to download a "public data" export. While this export is only accessible to administrators, in many configurations server administrators are not expected to have access to private messages and private streams. However, the "public data" export which administrators could generate contained the attachment contents for all attachments, even those from private messages and streams. Zulip Server version 5.4 contains a patch for this issue.
CVSS Score
4.9
EPSS Score
0.007
Published
2022-07-12
Zulip is an open-source team collaboration tool. Versions 2.1.0 through and including 5.2 are vulnerable to a logic error. A stream configured as private with protected history, where new subscribers should not be allowed to see messages sent before they were subscribed, when edited causes the server to incorrectly send an API event that includes the edited message to all of the stream’s current subscribers. This API event is ignored by official clients, but can be observed by using a modified client or the browser’s developer tools. This bug will be fixed in Zulip Server 5.3. There are no known workarounds.
CVSS Score
2.0
EPSS Score
0.005
Published
2022-06-25