ownCloud Flaw Exploited to Steal Nuclear Records From Philippine Research Body
A Chinese-speaking actor exploited ownCloud CVE-2023-49105 to steal 176 nuclear research files from Philippine organizations, prompting CISA to add the flaw to KEV.
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CVE-2023-49105
Improper Authentication in ownCloud Server Allows Unauthenticated File Access
CISA: ownCloud Improper Authentication Vulnerability
- CVSS 3.1
- 9.8 critical
- EPSS
- 43%p99
- Published
- ·
- Added to KEV
AI analysisSummaries by Vani AI
ownCloud Server versions from 10.6.0 up to (but not including) 10.13.1 accept WebDAV pre-signed URLs even when no signing key is configured for the file owner, an improper authentication flaw (CWE-287). A remote attacker who knows a victim's username can therefore access, modify, or delete that user's files without any credentials, with no privileges or user interaction required (CVSS 9.8). Any organization running a self-hosted ownCloud Server instance in the affected version range is exposed, especially internet-facing deployments. CISA added the flaw to its Known Exploited Vulnerabilities catalog on 2026-08-27, confirming exploitation in the wild, and EPSS assigns a 43.2% probability of exploitation within 30 days (99th percentile). No public proof-of-concept code is known, but recent press reports of attacks against ownCloud (including theft of records at a Philippine research body) indicate active targeting of ownCloud flaws.
What to do: Upgrade to ownCloud Server 10.13.1 or later immediately, prioritizing internet-facing instances, as the flaw is on CISA's KEV list with BOD 26-04 patching deadlines. Until patched, configure signing keys for users where possible and restrict internet exposure of the pre-signed URL/WebDAV endpoints, and review server logs for unauthenticated file access, modification, or deletion tied to known usernames. If mitigations are not available for a given deployment, follow BOD 26-04 guidance for cloud services or discontinue use of the product.
| Product | Affected |
|---|---|
| ownCloud Server (owncloud/core) | 10.6.0 through all versions before 10.13.1; fixed in 10.13.1 |
Estimated exposure
largelikely on the order of tens of thousands of self-hosted server deployments worldwide (no authoritative public install counts) — ownCloud Server is a widely deployed self-hosted file sync and share platform used by enterprises, universities, and public-sector bodies, but since no authoritative install counts are available this order-of-magnitude estimate is based on…
Order-of-magnitude estimate by the model from install counts, market share and public scan data it knows; verify before quoting.
Description · NVD
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.
KEVCISA Known Exploited Vulnerability
- Affected
- ownCloud ownCloud
- 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.
- Due date
- Ransomware use
- Unknown
- Vendors
- owncloud
- Products
- owncloud server
- Weakness
- CWE-287
- Vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
In the news
6 storiesU.S. CISA adds ownCloud, Linux Kernel, and JFrog Artifactory flaws to its Known Exploited Vulnerabilities catalog
CISA added actively exploited ownCloud, Linux kernel, and JFrog Artifactory flaws to its KEV catalog, setting August 30 and September 10 deadlines.
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CISA Adds Three Known Exploited Vulnerabilities to Catalog
CISA added three actively exploited vulnerabilities to its KEV catalog: CVE-2023-49105 (ownCloud), CVE-2026-53362 (Linux kernel), and CVE-2026-66384 (JFrog Artifactory).
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