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CVE-2023-28623

Unauthorized user can register an account in specific configurations in Zulip

LOW
3.7
CVSS Score
Published: May 19, 2023 at 09:04 PM UTC
Updated: June 17, 2026 at 05:48 AM UTC
1 product affected across 1 vendorZulip

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Severity
LOW3.7
Exploit prediction
EPSS 0.5%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Zulip· Zulip
95%
v < 6.2
Affected range stops below 6.2, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (2)

x_refsource_MISCPatchThird Party Advisory
Source: [email protected]
https://github.com/zulip/zulip/commit/3df1b4dd7c210c21deb6f829df19412b74573f8d
x_refsource_CONFIRMThird Party Advisory
Source: [email protected]
https://github.com/zulip/zulip/security/advisories/GHSA-7p62-pjwg-56rv

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

3.7LOW[email protected]
Attack Vector
NETWORK
Complexity
HIGH
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-285CWE-862

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