SB2020082625 - Multiple vulnerabilities in Zulip Server

Description

This security bulletin contains information about 4 secuirty vulnerabilities.

1) Cross-site scripting (CVE-ID: CVE-2020-12759)

The disclosed vulnerability allows a remote attacker to perform cross-site scripting (XSS) attacks.

The vulnerability exists due to insufficient sanitization of user-supplied data passed via the Dropbox webhook. A remote attacker can trick the victim to follow a specially crafted link and execute arbitrary HTML and script code in user's browser in context of vulnerable website.

Successful exploitation of this vulnerability may allow a remote attacker to steal potentially sensitive information, change appearance of the web page, perform phishing and drive-by-download attacks.

2) Input validation error (CVE-ID: CVE-2020-14194)

The vulnerability allows a remote non-authenticated attacker to read and manipulate data.

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

3) Improper access control (CVE-ID: CVE-2020-14215)

The vulnerability allows a remote attacker to gain unauthorized access to sensitive information.

The vulnerability exists due to improper access restrictions. A remote attacker can send a specially crafted request and gain unauthorized access to the affected application.

4) Improper Neutralization of Special Elements in Output Used by a Downstream Component (CVE-ID: CVE-2020-15070)

The vulnerability allows a remote authenticated user to execute arbitrary code.

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.

Remediation

Install update from vendor's website.

References

• https://blog.zulip.com/2020/06/17/zulip-server-2-1-5-security-release/
• https://blog.zulip.com/2020/06/26/zulip-server-2-1-7-security-release/