CVE-2025-64011Public exploitNetwork attack vector

Authenticated file preview disclosure via user-controlled fileId

Published Dec 12, 2025 · Updated Dec 12, 2025

Authorization bypass in Nextcloud Server 30.0.0 allows remote authenticated users to read other users' file previews. The /core/preview endpoint accepts an attacker-controlled fileId and returns the referenced file's generated preview without verifying that the requester owns or can access the source file. Any authenticated account can disclose preview-renderable content from unshared files, while no write or service-interruption impact is reported.

CVSS severity4.3
Medium
EPSS probability0.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authorization bypass in Nextcloud Server 30.0.0 allows remote authenticated users to read other users' file previews. The /core/preview endpoint accepts an attacker-controlled fileId and returns the referenced file's generated preview without verifying that the requester owns or can access the source file. Any authenticated account can disclose preview-renderable content from unshared files, while no write or service-interruption impact is reported.

The record

CVE
CVE-2025-64011
Published
Dec 12, 2025
Updated
Dec 12, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-639, T1530
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 12, 2025CVE publishedPublication date reported by the CVE source.
  2. Dec 12, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

4.3CISA-ADPCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-639Authorization Bypass Through User-Controlled Key
T1530Data from Cloud Storage

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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