CVE-2023-28623

lowpriority · track · 15OT risk · elevatedEPSS 0.005 · 45 %ileEUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

0.53% (45th) EPSS

CVSS 3.7 · low

Is it mine?

2 products

Check your exposure

Who says so?

3 sources

cnnvd · enisa_euvd · nvd

EPSS · scored 2026-10-28

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.

cvss

Technical severity, 0–10. One row per scoring source.

6.5

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · low–medium · 3.4–6.5

v3.13.7lowCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:Nprimary · NVD / NIST USexploitability 2.2 · impact 1.4

v3.16.5mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:Nsecondary · ENISA EU

v3.16.5mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:Nsecondary · security-advisories@github.comexploitability 2.2 · impact 4.2

v3.13.4lowCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N/E:Usecondary · CVSS-BT (t0sche)

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Trackcoordinatorcisa_ssvcUS

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-862USprimaryCWE-285US

affected products (2)

Products and version ranges known to be affected.

zulip zulip2.1.0, → 6.2enisa_euvdEU
zulip zulip< 6.2nvdUScpe:2.3:a:zulip:zulip:*:*:*:*:*:*:*:*

also known as (2)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd nvd NVD CVE.org MITRE

published 2023-05-19modified 2026-06-17

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+11503 more

references (7)

External citations — patches, advisories, analysis.

scry

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