CVE-2025-54856VulnerabilityPublished 23 Oct 2025

CVE-2025-54856: Six Apart Movable Type (Software Edition) · Cross-site scripting (XSS)

Affects Six Apart Movable Type (Software Edition)Source CVE Database V5

Not known to be exploited · CVSS 4.8 Medium.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 3.0 base score

4.8Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.2% chance of exploitation in 30 days – higher than 14% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.0/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: High
User Interaction: Required
Scope: Changed
Confidentiality: Low
Integrity: Low
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: High: The attacker is authorized with (i.e., requires) privileges that provide significant (e.g., administrative) control over the vulnerable component that could affect component-wide settings and files.
User Interaction: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 23 Oct 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-26.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
Six Apart Ltd. Movable Type (Software Edition)	Affected >=8.4.0 <=8.4.3 >=8.0.0 <=8.0.7	Fixed in–

AI-suggested

1. Immediately review and restrict ContentType Management privileges to only trusted and necessary personnel to reduce the risk of malicious input injection. 2. Apply any available patches or updates from Six Apart Ltd. as soon as they are released; if no patches are currently available, consider upgrading to unaffected versions if feasible. 3. Implement strict input validation and output encoding on the Edit ContentData page to neutralize potentially malicious scripts. 4. Employ Content Security Policy (CSP) headers to limit the execution of unauthorized scripts in browsers. 5. Monitor logs and user activities related to content management for unusual behavior or unauthorized changes. 6. Educate privileged users about the risks of XSS and safe content management practices. 7. Consider isolating or sandboxing the content management interface to limit the impact of any successful script execution. 8. Conduct regular security assessments and penetration testing focused on web application vulnerabilities, including XSS.

Description

Movable Type contains a stored cross-site scripting vulnerability in Edit ContentData page. If crafted input is stored by an attacker with "ContentType Management" privilege, an arbitrary script may be executed on the web browser of the user who accesses Edit ContentData page.

Impact

For European organizations, this vulnerability could lead to unauthorized disclosure of sensitive information and unauthorized actions performed under the context of privileged users, potentially compromising the integrity of published content or administrative functions. Organizations in media, publishing, and digital marketing sectors that use Movable Type are particularly at risk. The exploitation could facilitate further attacks such as session hijacking or privilege escalation if combined with other vulnerabilities. Although the vulnerability does not directly affect availability, the reputational damage and potential regulatory implications under GDPR due to data confidentiality breaches could be significant. The requirement for high privileges and user interaction limits the attack surface but does not eliminate risk, especially in large organizations with multiple administrators. The absence of known exploits in the wild provides a window for proactive mitigation before active exploitation occurs.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 30 Oct 2025, 04:38 UTC

Technical details

References

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