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Nextcloud CVE-2023-25821

HIGH
Improper Access Control (CWE-284)
2023-02-25 security-advisories@github.com
7.5
CVSS 3.1 · NVD
View

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V8 - Authorization Access control enforcement
MITRE ATT&CK

1 technique across 1 tactic: Defense Evasion

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Impact

CVSS score of 7.5 (HIGH). Attack characteristics: network attack vector, low complexity, no privileges required, no user interaction not required. Public proof-of-concept exploit code is available.

Exploit ScenarioDerived

This vulnerability can be exploited remotely over the network. Successful exploitation could compromise the high-severity affected system.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.9% exploitation probability (EPSS)

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AnalysisAI

Nextcloud is an Open Source private cloud software. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.

RemediationAI

A vendor patch is available. Apply the latest security update as soon as possible. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability is classified under CWE-284. Nextcloud is an Open Source private cloud software. Versions 24.0.4 and above, prior to 24.0.7, and 25.0.0 and above, prior to 25.0.1, contain Improper Access Control. Secure view for internal shares can be circumvented if reshare permissions are also given. This issue is patched in versions 24.0.7 and 25.0.1. No workaround is available. Affected products include: Nextcloud Nextcloud Server. Version information: prior to 24.0.7.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

DescriptionNVD

Nextcloud is an Open Source private cloud software. Versions 24.0.4 and above, prior to 24.0.7, and 25.0.0 and above, prior to 25.0.1, contain Improper Access Control. Secure view for internal shares can be circumvented if reshare permissions are also given. This issue is patched in versions 24.0.7 and 25.0.1. No workaround is available.

Threat Intelligence Overview

EPSS Score
0.9%
Top 43% exploitable
Exploit
POC
Public exploit code exists
Data Quality
3 sources
Confidence: Low

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC Yes
EPSS 0.9%
Patch available Yes
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
Poc
System Exposure· derived
Open
Automatable· derived
Yes
Human Impact· derived
Medium

Priority Score

59
Low Medium High Critical
KEV: 0
EPSS: +1
CVSS: +38
PoC: +20
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.

Affected Products (CPE)NVD

cpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:*:*:*:*
cpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:enterprise:*:*:*
cpe:2.3:a:nextcloud:nextcloud_server:25.0.0:*:*:*:*:*:*:*
cpe:2.3:a:nextcloud:nextcloud_server:25.0.0:*:*:*:enterprise:*:*:*
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