~/exploited / cve-2023-49105
CVE-2023-49105: ownCloud
According to CISA this vulnerability is already used in attacks (added on 27 August 2026).
Key facts
| CVE | CVE-2023-49105 |
|---|---|
| Vendor | ownCloud — ownCloud |
| Vulnerability | ownCloud Improper Authentication Vulnerability |
| Added | 27 August 2026 |
| Deadline (US agencies) | 30 August 2026 |
| Ransomware campaigns | unknown |
Description (CISA)
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.
Required action (CISA)
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.
What admins should do now
- Affected? Check whether ownCloud is in use and which version runs (package manager, admin UI,
--version). - Apply the vendor patch or workaround as soon as it exists. If that is not possible right away: restrict outside access (firewall, VPN, reverse proxy).
- Review logs back to 27 August 2026: unusual logins, new files, unexpected processes, outbound connections.
- If you suspect a compromise: isolate the system, rotate credentials, check the last backup from before the incident.
The deadline applies to US federal agencies. It is still a useful yardstick for everyone: when a flaw is attacked in the wild, waiting is not an option.
Sources
- CISA KEV Catalog
- NVD CVE-2023-49105
- owncloud.org/security
- owncloud.com/security-advisories/webdav-api-authentication-bypass-using-pre-sign
- www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-base
- www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizi
- nvd.nist.gov/vuln/detail/CVE-2023-49105
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