Resource exhaustion in Zulip Server - CVE-2019-16215
Published: September 18, 2019 / Updated: July 17, 2020
Vulnerability identifier: #VU30742
CSH Severity: Medium
CVSS v4: 7.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2019-16215
CWE-ID: CWE-400
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote authenticated user to perform a denial of service (DoS) attack.
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.
Affected software
Zulip Server
How to mitigate CVE-2019-16215
Install update from vendor's website.
Zulip Server - update to 2.0.5