Vulnerabilities

ownCloud Guests before 0.12.5 allows unauthenticated user enumeration via the /apps/guests/register/{email}/{token} endpoint. Because of insufficient validation of the supplied token in showPasswordForm, the server responds differently when an e-mail address corresponds to a valid pending guest user rather than a non-existent user.

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.

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.

An issue was discovered in ownCloud owncloud/oauth2 before 0.6.1, when Allow Subdomains is enabled. An attacker is able to pass in a crafted redirect-url that bypasses validation, and consequently allows an attacker to redirect callbacks to a Top Level Domain controlled by the attacker.

CVE-2023-49103 is an unauthenticated information disclosure flaw in ownCloud's graphapi app (0.2.x before 0.2.1 and 0.3.x before 0.3.1), which ships a third-party GetPhpInfo.php page that returns the full PHP phpinfo output when its URL is requested. An attacker with no credentials or user interaction simply accesses that URL over the network, and the phpinfo output reveals all of the webserver's environment variables plus other potentially sensitive configuration details. In containerized deployments these environment variables frequently include the ownCloud admin password, mail server credentials, and license key, giving attackers direct credentials for the server; notably, disabling the graphapi app does not remove the exposed file. Affected deployments are ownCloud installations running the vulnerable graphapi versions, especially ownCloud Docker images built after February 2023, while containers built before February 2023 are not vulnerable to the credential disclosure. Exploitation is confirmed in the wild: CISA added it to the Known Exploited Vulnerabilities catalog on 2023-11-30, the EPSS score is 78.4% (top percentile), and public reporting says threat actors have begun exploiting the flaw, though no public PoC is known.

Do: Upgrade the graphapi app to version 0.2.1 or 0.3.1, and note that simply disabling the app is not sufficient — ensure the GetPhpInfo.php file is removed per vendor instructions. Operators of containerized ownCloud deployments (Docker images from February 2023 onward) should assume the ownCloud admin password, mail server credentials, and license key were exposed, rotate them, and review web logs for requests to the GetPhpInfo.php URL. CISA KEV requires applying vendor mitigations or discontinuing use of the product if mitigations are unavailable.

The ownCloud Android app allows ownCloud users to access, share, and edit files and folders. Version 2.21.1 of the ownCloud Android app is vulnerable to SQL injection in `FileContentProvider.kt`. This issue can lead to information disclosure. Two databases, `filelist` and `owncloud_database`, are affected. In version 3.0, the `filelist` database was deprecated. However, injections affecting `owncloud_database` remain relevant as of version 3.0.

The Docker image of ownCloud Server through 10.11 contains a misconfiguration that renders the trusted_domains config useless. This could be abused to spoof the URL in password-reset e-mail messages.

ownCloud owncloud/core before 10.10.0 Improperly Removes Sensitive Information Before Storage or Transfer.

ownCloud owncloud/android before 2.20 has Incorrect Access Control for physically proximate attackers.

ownCloud owncloud/client before 2.9.2 allows Resource Injection by a server into the desktop client via a URL, leading to remote code execution.

The files_antivirus component before 1.0.0 for ownCloud mishandles the protection mechanism by which malicious files (that have been uploaded to a public share) are supposed to be deleted upon detection.

Server Side Request Forgery (SSRF) vulnerability exists in owncloud/user_ldap < 0.15.4 in the settings of the user_ldap app. Administration role is necessary for exploitation.

A receiver of a federated share with access to the database with ownCloud version before 10.8 could update the permissions and therefore elevate their own permissions.

ownCloud 10.7 has an incorrect access control vulnerability, leading to remote information disclosure. Due to a bug in the related API endpoint, the attacker can enumerate all users in a single request by entering three whitespaces. Secondary, the retrieval of all users on a large instance could cause higher than average load on the instance.

ownCloud owncloud/client before 2.7 allows DLL Injection. The desktop client loaded development plugins from certain directories when they were present.

In the ownCloud application before 2.15 for Android, the lock protection mechanism can be bypassed by moving the system date/time into the past.

ownCloud Server 10.x before 10.3.1 allows an attacker, who has one outgoing share from a victim, to access any version of any file by sending a request for a predictable ID number.

An issue was discovered in ownCloud before 10.4. Because of an SSRF issue (via the apps/files_sharing/external remote parameter), an authenticated attacker can interact with local services blindly (aka Blind SSRF) or conduct a Denial Of Service attack.

The File Firewall before 2.8.0 for ownCloud Server does not properly enforce file-type restrictions for public shares.

Deleting users with certain names caused system files to be deleted. Risk is higher for systems which allow users to register themselves and have the data directory in the web root. This affects ownCloud/core versions < 10.6.

When using an object storage like S3 as the file store, when a user creates a public link to a folder where anonymous users can upload files, and another user uploads a virus the files antivirus app would detect the virus but fails to delete it due to permission issues. This affects the files_antivirus component versions before 0.15.2 for ownCloud.

ownCloud (Core) before 10.5 allows XSS in login page 'forgot password.'

An attacker is logged in as a normal user and can somehow make admin to delete shared folders in ownCloud Server before 10.0.2.

Nextcloud Server before 9.0.54 and 10.0.1 & ownCloud Server before 9.1.2, 9.0.6, and 8.2.9 suffer from SMB User Authentication Bypass. Nextcloud/ownCloud include an optional and not by default enabled SMB authentication component that allows authenticating users against an SMB server. This backend is implemented in a way that tries to connect to a SMB server and if that succeeded consider the user logged-in. The backend did not properly take into account SMB servers that have any kind of anonymous auth configured. This is the default on SMB servers nowadays and allows an unauthenticated attacker to gain access to an account without valid credentials. Note: The SMB backend is disabled by default and requires manual configuration in the Nextcloud/ownCloud config file. If you have not configured the SMB backend then you're not affected by this vulnerability.

Nextcloud Server before 9.0.52 & ownCloud Server before 9.0.4 are vulnerable to a content-spoofing attack in the files app. The location bar in the files app was not verifying the passed parameters. An attacker could craft an invalid link to a fake directory structure and use this to display an attacker-controlled error message to the user.

ownCloud Server before 8.1.11, 8.2.x before 8.2.9, 9.0.x before 9.0.7, and 9.1.x before 9.1.3 allows remote authenticated users to cause a denial of service (server hang and logfile flooding) via a one bit BMP file.

ownCloud Desktop before 2.2.3 allows local users to execute arbitrary code and possibly gain privileges via a Trojan library in a "special path" in the C: drive.

ownCloud server before 8.2.6 and 9.x before 9.0.3, when the gallery app is enabled, allows remote attackers to download arbitrary images via a direct request.

Cross-site scripting (XSS) vulnerability in share.js in the gallery application in ownCloud Server before 9.0.4 and Nextcloud Server before 9.0.52 allows remote authenticated users to inject arbitrary web script or HTML via a crafted directory name.