Auth bypass in Nextcloud Server

CVE-2026-68493

After guessing a 62^15 complex unique identifier, a malicious logged in user was able to retrieve a list of memberships for a circle they are not a member of.

Vulnerability class: IDOR (Insecure Direct Object Reference)

Published · last modified .

CVSS v3 metric

CVSS v3 base score 3.1 (Low). Vector: CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N.

EPSS exploit prediction

EPSS: 0.002 (13.4th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 13th percentile — 13.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-68493: held from 0.002 to 0.002.

EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-68493?
CVE-2026-68493 is a low-severity vulnerability in Nextcloud Server, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 3.1/10. Published 2026-09-18.
How severe is CVE-2026-68493?
Low severity. CVSS v3 base score is 3.1 out of 10.