title: Race condition in Zulip
description: Zulip is an open source group chat application. Starting with version 4.0 and prior to version 4.11, Zulip is vulnerable to a race condition during account deactivation, where a simultaneous access by the user being deactivated may, in rare cases, allow continued access by the deactivated user. A patch is available in version 4.11 on the 4.x branch and version 5.0-rc1 on the 5.x branch. Upgrading to a fixed version will, as a side effect, deactivate any cached sessions that may have been leaked through this bug. There are currently no known workarounds.
problem types: CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
affected:
{
product: zulip
vendor: zulip
versions:
status: affected, version: >= 4.0, < 4.11
}
metrics:
cvssV3_1: [
attackComplexity: LOW
attackVector: NETWORK
availabilityImpact: NONE
baseScore: 5.4
baseSeverity: MEDIUM
confidentialityImpact: LOW
integrityImpact: LOW
privilegesRequired: LOW
scope: UNCHANGED
userInteraction: NONE
vectorString: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
version: 3.1
]