Auth bypass in ownCloud Server
CVE-2023-49105
An issue was discovered in ownCloud owncloud/core before 10.13.1. An attacker can access, modify, or delete any file without authentication if the username of a victim is known, and the victim has no signing-key configured. This occurs because pre-signed URLs can be accepted even when no signing-key is configured for the owner of the files. The earliest affected version is 10.6.0.
Vulnerability class: Broken Authentication
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.429 (98.7th percentile), scored .
Moderate probability of exploitation in the next 30 days — watch for active exploitation reports. 99th percentile — 98.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.432 · newest: 0.429 · change: -0.003
Affected products
Weakness classification (CWE)
CISA KEV (Known Exploited Vulnerabilities)
This CVE is on the CISA KEV catalog, added on . CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.
BOD 22-01 due date: .
Required action: 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.
Public proof-of-concept exploits
References
- owncloud.org/security (Product)
- owncloud.com/security-advisories/webdav-api-authentication-bypass-using-pre-sig… (Vendor Advisory)
- 134c704f-9b21-4f2e-91b3-4a467353bcc0 (Third Party Advisory)
- 134c704f-9b21-4f2e-91b3-4a467353bcc0 (US Government Resource)
Frequently asked questions
- What is CVE-2023-49105?
- CVE-2023-49105 is a critical-severity vulnerability in ownCloud Server, classified under Improper Authentication. CVSS score: 9.8/10. Published 2023-11-21.
- How severe is CVE-2023-49105?
- Critical severity. CVSS v3 base score is 9.8 out of 10.
- Is CVE-2023-49105 known to be exploited?
- Yes. CVE-2023-49105 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2026-08-27), indicating it is being actively exploited. 3 public proof-of-concept repositories are indexed.