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CVE-2023-28623

MediumCVSS 6.5 / 10
Published May 19, 2023·Last modified Apr 10, 2026
Affected Components(0)

No affected components available

Description

Zulip is an open-source team collaboration tool with unique topic-based threading. In the event that 1: ZulipLDAPAuthBackend and an external authentication backend (any aside of ZulipLDAPAuthBackend and EmailAuthBackend) are the only ones enabled in AUTHENTICATION_BACKENDS in /etc/zulip/settings.py and 2: The organization permissions don't require invitations to join. An attacker can create a new account in the organization with an arbitrary email address in their control that's not in the organization's LDAP directory. The impact is limited to installations which have this specific combination of authentication backends as described above in addition to having Invitations are required for joining this organization organization permission disabled. This issue has been addressed in version 6.2. Users are advised to upgrade. Users unable to upgrade may enable the Invitations are required for joining this organization organization permission to prevent this issue.

Risk Scores
Base Score
6.5

The vulnerability can be exploited over the network without needing physical access. It is difficult for an attacker to exploit this vulnerability and may require special conditions. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a high impact on the confidentiality of the information. There is a low impact on the integrity of the data.

Threat Intelligence
6.0

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
0.53%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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