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CVE-2025-46340
No affected components available
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 vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability. The vulnerability can affect other systems as well, not just the initial system. There is a low impact on the confidentiality of the information. There is a low impact on the integrity of the data.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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