What is CVE-2023-33183?

CVE-2023-33183 is a low-severity vulnerability in Nextcloud Calendar, classified under Improper Authorization. CVSS score: 2.6/10. Published 2023-05-30.

How severe is CVE-2023-33183?

Low severity. CVSS v3 base score is 2.6 out of 10.

Auth bypass in Nextcloud Calendar

CVE-2023-33183

Calendar app for Nextcloud easily sync events from various devices with your Nextcloud. Some internal paths of the website are disclosed when the SMTP server is unavailable. It is recommended that the Calendar app is updated to 3.5.5 or 4.2.3

Published 2023-05-30 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 2.6 (Low). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:N/A:N.

EPSS exploit prediction

EPSS: 0.004 (36.7th percentile), scored 2026-10-20.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 37th percentile — 36.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000

Affected products

Nextcloud Calendar
Nextcloud Security-Advisories — versions < 3.5.5, < 4.2.3

Weakness classification (CWE)

CWE-285 — Improper Authorization

References

github.com/nextcloud/security-advisories/security/advisories/GHSA-2792-2734-hr7j (Vendor Advisory)
github.com/nextcloud/calendar/pull/4938 (Patch)

Frequently asked questions

What is CVE-2023-33183?: CVE-2023-33183 is a low-severity vulnerability in Nextcloud Calendar, classified under Improper Authorization. CVSS score: 2.6/10. Published 2023-05-30.
How severe is CVE-2023-33183?: Low severity. CVSS v3 base score is 2.6 out of 10.