title: Expression Always True vulnerability in Zulip Server
description: Zulip is an open-source team collaboration tool. Versions 2.1.0 through and including 5.2 are vulnerable to a logic error. A stream configured as private with protected history, where new subscribers should not be allowed to see messages sent before they were subscribed, when edited causes the server to incorrectly send an API event that includes the edited message to all of the stream’s current subscribers. This API event is ignored by official clients, but can be observed by using a modified client or the browser’s developer tools. This bug will be fixed in Zulip Server 5.3. There are no known workarounds.
problem types: CWE-571: Expression is Always True
affected:
{
product: zulip
vendor: zulip
versions:
status: affected, version: >= 2.1.0, < 5.3
}
metrics:
cvssV3_1: [
attackComplexity: HIGH
attackVector: NETWORK
availabilityImpact: NONE
baseScore: 2
baseSeverity: LOW
confidentialityImpact: LOW
integrityImpact: NONE
privilegesRequired: HIGH
scope: UNCHANGED
userInteraction: REQUIRED
vectorString: CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:L/I:N/A:N
version: 3.1
]