CVE - CVE-2025-46340

CVE-ID
CVE-2025-46340	Learn more at National Vulnerability Database (NVD) • CVSS Severity Rating • Fix Information • Vulnerable Software Versions • SCAP Mappings • CPE Information
Description
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.
References
Note: References are provided for the convenience of the reader to help distinguish between vulnerabilities. The list is not intended to be complete.
MISC:https://github.com/misskey-dev/misskey/commit/d10fdfe9738b17a9d81037c031b40a2cc4cb8038 URL:https://github.com/misskey-dev/misskey/commit/d10fdfe9738b17a9d81037c031b40a2cc4cb8038 MISC:https://github.com/misskey-dev/misskey/security/advisories/GHSA-3p2w-xmv5-jm95 URL:https://github.com/misskey-dev/misskey/security/advisories/GHSA-3p2w-xmv5-jm95
Assigning CNA
GitHub (maintainer security advisories)
Date Record Created
20250422	Disclaimer: The record creation date may reflect when the CVE ID was allocated or reserved, and does not necessarily indicate when this vulnerability was discovered, shared with the affected vendor, publicly disclosed, or updated in CVE.
Phase (Legacy)
Assigned (20250422)
Votes (Legacy)

Comments (Legacy)

Proposed (Legacy)
N/A
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