CVE-2021-41115

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).

Related CPE's

CvssV3 impact

Version

3.1

VectorString

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

AttackVector

NETWORK

AttackComplexity

LOW

PrivilegesRequired

LOW

UserInteraction

NONE

Scope

UNCHANGED

ConfidentialityImpact

NONE

IntegrityImpact

NONE

AvailabilityImpact

HIGH

BaseScore

6.5

BaseSeverity

MEDIUM

CvssV2 impact

AccessComplexity

LOW

ConfidentialityImpact

NONE

AvailabilityImpact

PARTIAL

IntegrityImpact

NONE

BaseScore

4

VectorString

AV:N/AC:L/Au:S/C:N/I:N/A:P

Version

2.0

AccessVector

NETWORK

Authentication

SINGLE