CVE-2021-41115

 

Published at: - 08-10-2021 01:15

Last modified: - 10-09-2022 04:38

Total changes: - 5

Description

Zulip is an open source team chat server. In affected versions Zulip allows organization administrators on a server to configure "linkifiers" that automatically create links from messages that users send, detected via arbitrary regular expressions. Malicious organization administrators could subject the server to a denial-of-service via regular expression complexity attacks; most simply, by configuring a quadratic-time regular expression in a linkifier, and sending messages that exploited it. A regular expression attempted to parse the user-provided regexes to verify that they were safe from ReDoS -- this was both insufficient, as well as _itself_ subject to ReDoS if the organization administrator entered a sufficiently complex invalid regex. Affected users should [upgrade to the just-released Zulip 4.7](https://zulip.readthedocs.io/en/latest/production/upgrade-or-modify.html#upgrading-to-a-release), or [`main`](https://zulip.readthedocs.io/en/latest/production/upgrade-or-modify.html#upgrading-from-a-git-repository).

Common Vulnerability Scoring System (CVSS)

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

 

Verification logic

 

Reference

• https://github.com/zulip/zulip/security/advisories/GHSA-4h36-mqfq-42jg
• https://securitylab.github.com/advisories/GHSL-2021-118-zulip-zulip/
• https://github.com/zulip/zulip/commit/e2d303c1bb5f538d17dc3d9134bc8858bdece781

 

Keywords

NVD

 

CVE-2021-41115

 

CVE

 

Common vulnerabilities & exposures

 

CVSS

 

Common vulnerability scoring system

 

Security

 

Vulnerabilities

 

Exposures