CVE-2025-46340Public exploitNetwork attack vector

Interface spoofing via unescaped preview-image CSS

Published May 5, 2025 · Updated May 5, 2025

CSS injection in Misskey 12.0.0 through 2025.4.0 allows remote attackers to alter URL-preview styling through a crafted page. UrlPreviewService.wrap returns non-HTTP thumbnail URLs unchanged, and MkUrlPreview interpolates the returned string into a background-image style without CSS-safe binding. Rendering a note linked to the crafted page can cover interface content with attacker-controlled styling, enabling deceptive credential prompts and exposing a viewer's address through direct resource requests.

CVSS severity7.2
High
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

CSS injection in Misskey 12.0.0 through 2025.4.0 allows remote attackers to alter URL-preview styling through a crafted page. UrlPreviewService.wrap returns non-HTTP thumbnail URLs unchanged, and MkUrlPreview interpolates the returned string into a background-image style without CSS-safe binding. Rendering a note linked to the crafted page can cover interface content with attacker-controlled styling, enabling deceptive credential prompts and exposing a viewer's address through direct resource requests.

The record

CVE
CVE-2025-46340
Published
May 5, 2025
Updated
May 5, 2025
Vendor
Misskey Project
Product
Misskey
Classifications
CWE-20, CWE-116
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 5, 2025CVE publishedPublication date reported by the CVE source.
  2. May 5, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 12.0.0, < 2025.4.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Misskey Project · Misskeyversion=>= 12.0.0, < 2025.4.1

Published CVSS scores

5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
7.2GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-20Improper Input Validation
CWE-116Improper Encoding or Escaping of Output

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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