misskey-dev misskey 2025.2.0-alpha.0 UrlPreviewService/MkUrlPreview information exposure

Summaryinfo

A vulnerability was found in misskey-dev misskey. It has been declared as critical. This affects the function UrlPreviewService/MkUrlPreview. Such manipulation leads to information exposure. This vulnerability is uniquely identified as CVE-2025-46340. The attack can be launched remotely. No exploit exists. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in misskey-dev misskey. It has been rated as critical. Affected by this issue is the function UrlPreviewService/MkUrlPreview. The manipulation with an unknown input leads to a information exposure vulnerability. Using CWE to declare the problem leads to CWE-209. The product generates an error message that includes sensitive information about its environment, users, or associated data. Impacted is confidentiality, integrity, and availability. CVE summarizes:

Misskey is an open source, federated social media platform. Starting in version 12.0.0 and prior to version 2025.4.1, due to an oversight in the validation performed in `UrlPreviewService` and `MkUrlPreview`, it is possible for an attacker to inject arbitrary CSS into the `MkUrlPreview` component. `UrlPreviewService.wrap` falls back to returning the original URL if it's using a protocol that is likely to not be understood by Misskey, IE something other than `http` or `https`. This both can de-anonymize users and_allow further attacks in the client. Additionally, `MkUrlPreview` doesn't escape CSS when applying a `background-image` property, allowing an attacker to craft a URL that applies arbitrary styles to the preview element. Theoretically, an attacker can craft a CSS injection payload to create a fake error message that can deceive the user into giving away their credentials or similar sensitive information. Version 2025.4.1 contains a patch for the issue.

The advisory is available at github.com. This vulnerability is handled as CVE-2025-46340 since 04/23/2025. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Technical details are known, but there is no available exploit. This vulnerability is assigned to T1592 by the MITRE ATT&CK project.

Upgrading to version 2025.4.1 eliminates this vulnerability. Applying the patch d10fdfe9738b17a9d81037c031b40a2cc4cb8038 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Vendor

• misskey-dev

Name

• misskey

Version

• 2025.2.0-alpha.0

License

• open-source

Website

• Product: https://github.com/misskey-dev/misskey/

CPE 2.3info

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CPE 2.2info

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