Medium severity · published Sep 18, 2019
CVE-2019-16215
The Markdown parser in Zulip server before 2.0.5 used a regular expression vulnerable to exponential backtracking
6.5
CVSS
1.2%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)1.2% · higher than 69% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
ZS
Zulip Server · Zulip
before 2.0.5 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2019-16215
CVE.org
https://www.cve.org/CVERecord?id=CVE-2019-16215
Vendor Advisory
https://blog.zulip.org/2019/09/11/zulip-server-2-0-5-security-release/
Patch
https://github.com/zulip/zulip/commit/5797f013b3be450c146a4141514bda525f2f1b51
More from Zulip Server
9.8
CVE-2022-21706
Multi-use invitations can grant access to other organizations in Zulip
9.8
CVE-2019-18933
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…
8.8
CVE-2020-15070
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…
8.8
CVE-2017-0910
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…
8.2
CVE-2025-31478
Zulip Authentication Backend Configuration Bypass