Security Resilience

CVE-2023-28646

Auth Bypass in Nextcloud 3.7.0 – 3.24.1

Auth Bypass
Published
30 March 2023
Modified
21 November 2024
Patch / advisory
View advisory
CVSS Score v3.1 4.4
Click a component to see what it means
Raw vectorCVSS:3.1/AV:P/AC:H/PR:L/UI:R/S:C/C:L/I:L/A:L
EPSS Score 0.0023 13th percentile
Risk Priority 33 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2023-28646 is a medium-severity Improper Preservation of Permissions (CWE-281) vulnerability in Nextcloud Nextcloud. Its CVSS base score is 4.4 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Data Obfuscation (T1001); ranked at the 13th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

OWASP Top 10 for Web (2025)

A01:2025 Broken Access ControlA07:2025 Authentication Failures

EU & UK References

Vulnerability Data

Nextcloud android is an android app for interfacing with the nextcloud home server ecosystem. In versions from 3.7.0 and before 3.24.1 an attacker that has access to the unlocked physical device can bypass the Nextcloud Android Pin/passcode protection via a…

more

thirdparty app. This allows to see meta information like sharer, sharees and activity of files. It is recommended that the Nextcloud Android app is upgraded to 3.24.1. There are no known workarounds for this vulnerability.

CWE(s)
CWE-281CWE-287NVD-CWE-noinfo

Related Threats

MITRE ATT&CK Enterprise Techniques

T1001 Data Obfuscation Command And Control
Adversaries may obfuscate command and control traffic to make it more difficult to detect.
attack.mitre.org →
T1003.002 Security Account Manager Credential Access
Adversaries may attempt to extract credential material from the Security Account Manager (SAM) database either through in-memory techniques or through the Windows Registry where the SAM database is stored.
attack.mitre.org →
T1003.005 Cached Domain Credentials Credential Access
Adversaries may attempt to access cached domain credentials used to allow authentication to occur in the event a domain controller is unavailable.
attack.mitre.org →
T1005 Data from Local System Collection
Adversaries may search local system sources, such as file systems, configuration files, local databases, virtual machine files, or process memory, to find files of interest and sensitive data prior to Exfiltration.
attack.mitre.org →
T1011 Exfiltration Over Other Network Medium Exfiltration
Adversaries may attempt to exfiltrate data over a different network medium than the command and control channel.
attack.mitre.org →
T1016 System Network Configuration Discovery Discovery
Adversaries may look for details about the network configuration and settings, such as IP and/or MAC addresses, of systems they access or through information discovery of remote systems.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2023-28647Same product: Nextcloud Nextcloud
CVE-2023-49790Same product: Nextcloud Nextcloud
CVE-2024-22404Same vendor: Nextcloud
CVE-2024-22401Same vendor: Nextcloud
CVE-2024-22402Same vendor: Nextcloud
CVE-2023-25817Same vendor: Nextcloud
CVE-2024-37882Same vendor: Nextcloud
CVE-2023-28999Same product: Nextcloud Nextcloud
CVE-2025-66515Same vendor: Nextcloud
CVE-2024-37313Same vendor: Nextcloud

Affected Assets

nextcloud
nextcloud
3.7.0 — 3.24.1

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)
  • 5 hardening rules · 2 OS baselines
Validate
Prove the fix (OWASP ASVS)

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Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

AC-9 Previous Logon Notification
addresses: CWE-287

Detects unauthorized successful logons resulting from improper authentication implementations.

AT-1 Policy and Procedures
addresses: CWE-287

Documented procedures ensure personnel are trained on authentication mechanisms, tangibly lowering the risk of improper authentication being exploited.

AT-2 Literacy Training and Awareness
addresses: CWE-287

Security awareness training instructs users on secure authentication practices and avoiding credential compromise.

AT-3 Role-based Training
addresses: CWE-287

Training on authentication mechanisms and best practices decreases the occurrence of improper authentication.

AU-10 Non-repudiation
addresses: CWE-287

Non-repudiation requires strong authentication mechanisms to irrefutably attribute performed actions to specific individuals or processes.

AU-14 Session Audit
addresses: CWE-287

Session content review can reveal authentication bypasses or failures in session establishment.

AU-6 Audit Record Review, Analysis, and Reporting
addresses: CWE-287

Review of authentication-related audit records can detect improper authentication mechanisms or bypasses.

CA-2 Control Assessments
addresses: CWE-287

Assessments check authentication mechanisms for correct implementation and effectiveness, reducing successful authentication bypass attempts.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.AA-05 partial match
blocks

Enforcing least-privilege permission policies and reviews directly prevents incorrect permission propagation on copy/restore/share operations.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.5.14 Information transfer partial match
removes
A.5.15 Access control partial match
removes
A.5.16 Identity management partial match
removes
A.5.17 Authentication information partial match
removes
A.5.18 Access rights partial match
removes
A.8.10 Information deletion partial match
removes

Hardening callouts derived

Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (higher-evidence rows only; rows rated `none` are excluded).

Windows Server 2019 (1 rule)
  • V-205743 Windows Server 2019 organization created Active Directory Organizational Unit (OU) objects must have proper access control permissions. blocks CWE-281

References