What is CVE-2025-64011?

CVE-2025-64011 is a medium-severity vulnerability in Nextcloud Server, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 4.3/10. Published 2025-12-12.

How severe is CVE-2025-64011?

Medium severity. CVSS v3 base score is 4.3 out of 10.

Auth bypass in Nextcloud Server

CVE-2025-64011

Nextcloud Server 30.0.0 is vulnerable to an Insecure Direct Object Reference (IDOR) in the /core/preview endpoint. Any authenticated user can access previews of arbitrary files belonging to other users by manipulating the fileId parameter. This allows unauthorized disclosure of sensitive data, such as text files or images, without prior sharing permissions.

Vulnerability class: IDOR (Insecure Direct Object Reference)

Published 2025-12-12 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N.

EPSS exploit prediction

EPSS: 0.003 (18.1th percentile), scored 2026-10-03.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 18th percentile — 18.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: +0.000

Affected products

Nextcloud Server — versions 30.0.0

Weakness classification (CWE)

CWE-639 — Authorization Bypass Through User-Controlled Key

References

drive.google.com/file/d/1eD3PN-u1caZYgGH96XHmJ7h_OBXEAHW4/view (Exploit)
nextcloud.com (Product)
gist.github.com/tarekramm/586dfe2d113fedfee6d71182570fc090 (Exploit, Third Party Advisory)

Frequently asked questions

What is CVE-2025-64011?: CVE-2025-64011 is a medium-severity vulnerability in Nextcloud Server, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 4.3/10. Published 2025-12-12.
How severe is CVE-2025-64011?: Medium severity. CVSS v3 base score is 4.3 out of 10.