CVE-2023-48303Network attack vector

User storage disruption via cross-user credential changes

Published Nov 21, 2023 · Updated Aug 2, 2024

Improper access control in Nextcloud Server allows remote authenticated administrators to alter other users' external-storage credentials. The files_external AjaxController treated site administrators as authorized to edit any user's external-storage configuration instead of restricting edits to the owning user. Exploitation requires administrator privileges and user interaction, and changed authentication details can interrupt the affected user's external-storage access.

CVSS severity2.4
Low
EPSS probability0.67%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper access control in Nextcloud Server allows remote authenticated administrators to alter other users' external-storage credentials. The files_external AjaxController treated site administrators as authorized to edit any user's external-storage configuration instead of restricting edits to the owning user. Exploitation requires administrator privileges and user interaction, and changed authentication details can interrupt the affected user's external-storage access.

The record

CVE
CVE-2023-48303
Published
Nov 21, 2023
Updated
Aug 2, 2024
Vendor
Nextcloud GmbH
Product
Security Advisories
Classifications
CWE-284
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Nov 21, 2023CVE publishedPublication date reported by the CVE source.
  2. Aug 2, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 25.0.0, < 25.0.11
  2. Affected versionversion=>= 26.0.0, < 26.0.6
  3. Affected versionversion=>= 27.0.0, < 27.1.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

Nextcloud GmbH · Security Advisoriesversion=>= 25.0.0, < 25.0.11; version=>= 26.0.0, < 26.0.6; version=>= 27.0.0, < 27.1.0

Published CVSS scores

2.4GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:N/I:N/A:L
2.7NIST NVDCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-284Improper Access Control

Public exploit references

No public exploit references are available in this record.

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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