What is the CVSS score of CVE-2023-48239?

CVE-2023-48239 has a CVSS 3.1 base score of 7.1 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H. EPSS exploitation probability: 0.9%.

Is there a public PoC exploit available for CVE-2023-48239?

Yes, a public proof-of-concept exploit is available for CVE-2023-48239. Prioritise patching immediately. EPSS: 0.9%.

Is there a patch available for CVE-2023-48239?

Yes, a patch is available for CVE-2023-48239. Update the affected software to the latest version immediately.

Nextcloud Server CVE-2023-48239

HIGH

Improper Access Control (CWE-284)

2023-11-21 security-advisories@github.com

Authentication Bypass Nextcloud Server Nextcloud

7.1

CVSS 3.1 · NVD

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Vulnerability Assessment

Weakness	CWE CWE-284 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. Sign in to read
Impact	CVSS score of 7.1 (HIGH). Attack characteristics: network attack vector, low complexity, low 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 Server provides data storage for Nextcloud, an open source cloud platform. Rated high severity (CVSS 7.1), this vulnerability is remotely exploitable, 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 Server provides data storage for Nextcloud, an open source cloud platform. Starting in version 25.0.0 and prior to versions 25.0.13, 26.0.8, and 27.1.3 of Nextcloud Server and starting in version 20.0.0 and prior to versions 20.0.14.16, 21.0.9.13, 22.2.10.15, 23.0.12.12, 24.0.12.8, 25.0.13, 26.0.8, and 27.1.3 of Nextcloud Enterprise Server, a malicious user could update any personal or global external storage, making them inaccessible for everyone else as well. Nextcloud Server 25.0.13, 26.0.8, and 27.1.3 and Nextcloud Enterprise Server is upgraded to 20.0.14.16, 21.0.9.13, 22.2.10.15, 23.0.12.12, 24.0.12.8, 25.0.13, 26.0.8, and 27.1.3 contain a patch for this issue. As a workaround, disable app files_external. This workaround also makes the external storage inaccessible but retains the configurations until a patched version has been deployed. Affected products include: Nextcloud Nextcloud Server. Version information: version 25.0.0.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 7.1 HIGH

AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

Low

Availability

High

DescriptionNVD

Nextcloud Server provides data storage for Nextcloud, an open source cloud platform. Starting in version 25.0.0 and prior to versions 25.0.13, 26.0.8, and 27.1.3 of Nextcloud Server and starting in version 20.0.0 and prior to versions 20.0.14.16, 21.0.9.13, 22.2.10.15, 23.0.12.12, 24.0.12.8, 25.0.13, 26.0.8, and 27.1.3 of Nextcloud Enterprise Server, a malicious user could update any personal or global external storage, making them inaccessible for everyone else as well. Nextcloud Server 25.0.13, 26.0.8, and 27.1.3 and Nextcloud Enterprise Server is upgraded to 20.0.14.16, 21.0.9.13, 22.2.10.15, 23.0.12.12, 24.0.12.8, 25.0.13, 26.0.8, and 27.1.3 contain a patch for this issue. As a workaround, disable app files_external. This workaround also makes the external storage inaccessible but retains the configurations until a patched version has been deployed.

Threat Intelligence Overview

EPSS Score

0.9%

Top 43% exploitable

Exploit

POC

Public exploit code exists

Data Quality

3 sources

Confidence: Low

NVD

CVE.org

EPSS

GitHub

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

Human Impact· derived

Medium

Priority Score

Low Medium High Critical

KEV: 0

EPSS: +1

CVSS: +36

PoC: +20

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Authentication Bypass CRITICAL

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:*:*:*:*:enterprise:*:*:*

cpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:-:*:*:*

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

cpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:-:*:*:*

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

cpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:-:*:*:*

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

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Same weakness CWE-284 – Improper Access Control

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CVE-2015-3306 CRITICAL POC

10.0

CVE-2012-4681 CRITICAL POC

9.8

CVE-2011-3544 CRITICAL POC

9.8

CVE-2012-1723 CRITICAL POC

9.8

CVE-2012-5076 CRITICAL POC

9.8

CVE-2014-3120 HIGH POC

8.1

CVE-2013-2423 LOW POC

3.7

CVE-2016-3427 CRITICAL

9.8

Same technique Authentication Bypass

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CVE-2023-22515 CRITICAL POC

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CVE-2013-2465 CRITICAL POC

9.8

CVE-2022-40684 CRITICAL POC

9.8

CVE-2025-61882 CRITICAL POC

9.8

CVE-2024-0012 CRITICAL POC

9.3

References

Advisories & patches

PATCH https://github.com/nextcloud/server/pull/41123 ADVISORY https://github.com/nextcloud/security-advisories/security/advisories/GHSA-f962-hw26-g267

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