CVE-2023-49105 - ownCloud Improper Authentication Vulnerability

Technical Severity

CVSS v3.1 Metrics

CRITICAL

9.8 / 10

Minimal Risk Critical

Vector Specification

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitation Likelihood

EPSS Prediction

11.07 %

Predictive Probability

Percentile Rank

95.6 th

Documented as more likely to be exploited than 95.6% of known CVEs.

Detection Date

Aug 27, 2026

Remediation Due

Aug 30, 2026

CISA Catalog Active

Threat Analysis

ownCloud contains an improper authentication vulnerability that allows an attacker to access, modify, or delete any file without authentication if the username of a victim is known, and the victim has no signing-key configured.

Remediation Directive

Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

External Intelligence

https://owncloud.org/security

https://owncloud.com/security-advisories/webdav-api-authentication-bypass-using-pre-signed-urls/

CISA

CISA Advisory

https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk

CISA

CISA Advisory

https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk

NVD

National Vulnerability Database

https://nvd.nist.gov/vuln/detail/CVE-2023-49105