CVE-2025-54856Network attack vector

Stored script execution via crafted content data

Published Oct 23, 2025 · Updated Oct 23, 2025

Stored XSS in Six Apart Movable Type affected editions allows remote authenticated users to execute script in an editor's browser. Public advisories identify Edit ContentData but do not disclose which field fails to neutralize stored input before rendering. The attacker needs ContentType Management privilege, and a victim must open the affected edit page; execution is confined to that user's browser context.

CVSS severity4.8
Medium
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in Six Apart Movable Type affected editions allows remote authenticated users to execute script in an editor's browser. Public advisories identify Edit ContentData but do not disclose which field fails to neutralize stored input before rendering. The attacker needs ContentType Management privilege, and a victim must open the affected edit page; execution is confined to that user's browser context.

The record

CVE
CVE-2025-54856
Published
Oct 23, 2025
Updated
Oct 23, 2025
Vendor
Six Apart Ltd.
Product
Movable Type Advanced
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 23, 2025CVE publishedPublication date reported by the CVE source.
  2. Oct 23, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=7 r.5509 and earlier (7 series)
  2. Affected versionversion=8.0.0 to 8.0.7 (8.0 series)
  3. Affected versionversion=8.4.0 to 8.4.3 (8.4 series)

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Six Apart Ltd. · Movable Type Advancedversion=7 r.5509 and earlier (7 series); version=8.0.0 to 8.0.7 (8.0 series); version=8.4.0 to 8.4.3 (8.4 series)
Six Apart Ltd. · Movable Type Premium (Cloud Edition)version=1.67 (1 series); version=2.10 (2 series)
Six Apart Ltd. · Movable Type Premiumversion=1.67 and earlier (1 series); version=2.10 and earlier (2 series)
Six Apart Ltd. · Movable Type Premium (Advanced Edition)version=1.67 and earlier (1 series); version=2.10 and earlier (2 series)
Six Apart Ltd. · Movable Typeversion=7 r.5509 and earlier (7 series); version=8.0.0 to 8.0.7 (8.0 series); version=8.4.0 to 8.4.3 (8.4 series)
Six Apart Ltd. · Movable Type (Cloud Edition)version=7 r.5509 (7 series); version=8.7.0 (8 series)

Published CVSS scores

4.6JPCERT/CCCVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
4.8JPCERT/CCCVSS:3.0/AV:N/AC:L/PR:H/UI:R/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007JavaScript/JScript

Public exploit references

No public exploit references are available in this record.

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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