NPM · AUGUST 2026 · EARLY WARNING

ownCloud Improper Authentication Vulnerability Under Investigation

EARLY WARNING · UNCONFIRMED. This page describes a developing threat that 0Day surfaced from early signals and has not yet independently confirmed. Details may change. Always verify against the primary sources before acting.
Severity
HIGH
Affected component
owncloud (npm)
Patched version
Not yet available
CVE-2023-49105

An improper authentication vulnerability in ownCloud is under investigation. It appears to allow attackers to access, modify, or delete files without authentication if the victim has no signing-key configured.

What happened

ownCloud is reportedly affected by an improper authentication vulnerability tracked as CVE-2023-49105. This vulnerability 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. The vulnerability is exploited in the wild, as indicated by the CISA Known Exploited Vulnerabilities Catalog. To assess your exposure, check if you are using ownCloud and whether your users have signing-keys configured.

The vulnerability was first flagged on 2026-08-27T00:00:00+00:00. Threat actors have reportedly exploited this flaw to gain initial access, resulting in stolen data. The specific version range of ownCloud affected by this vulnerability has not been authoritatively published yet. Therefore, it is recommended to upgrade to the latest version of ownCloud and ensure all users have signing-keys configured.

What to do about it

How 0Day would have caught this

MATCHED TO YOUR ACTUAL DEPENDENCY GRAPH0Day matches every incoming threat signal against your GitHub organization’s full dependency graph, including transitive dependencies. If owncloud is anywhere in your dependency tree, the engineers who own the affected repositories get a push alert the moment it is flagged — no manual audit to remember to run.

Read how this differs from waiting on a scanner to catch a known advisory, or see the exact, read-only access 0Day needs to do this for an organization.

Frequently asked questions

Am I affected?

You may be affected if you are using ownCloud and have users without signing-keys configured. The specific version range of ownCloud affected by this vulnerability has not been authoritatively published yet.

What should I do right now?

Upgrade to the latest version of ownCloud and ensure all users have signing-keys configured. Monitor the primary sources for updates on the vulnerability and any official fixes.

Has this been exploited in the wild?

Yes, the vulnerability is reportedly exploited in the wild, as indicated by the CISA Known Exploited Vulnerabilities Catalog.

Sources

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