CVE-2025-46340

mediumpriority · track · 22EPSS 0.003 · 17 %ileEUUS
grimoire priorityP3 · Track
Exploitable?
—
no known exploitation
Likely / severe?
0.25% (17th) EPSS
CVSS 5.4 · medium
Is it mine?
2 products
Check your exposure
Who says so?
3 sources
cnnvd · enisa_euvd · nvd

EPSS · scored 2026-10-28

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.

01

cvss

Technical severity, 0–10. One row per scoring source.

7.2
010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 5–7.2

v3.15.4mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:Nprimary · NVD / NIST USexploitability 2.8 · impact 2.5
v3.17.2highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:Nsecondary · ENISA EU
v3.17.2highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:Nsecondary · security-advisories@github.comexploitability 3.9 · impact 2.7
v3.15mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N/E:Usecondary · CVSS-BT (t0sche)
02

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: poc · Automatable: yes · Technical Impact: partialcoordinatorcisa_ssvcUS
03

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-116USCWE-20US
04

affected products (2)

Products and version ranges known to be affected.

05

also known as (2)

Other names and identifiers for this entity.

06

sources

Which sources assert this record, and when.

cnnvdenisa_euvdnvdNVDCVE.orgMITRE
published 2025-05-05modified 2026-06-17
07

references (8)

External citations — patches, advisories, analysis.

scry

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