CVE-2026-21393

Movable Type contains a stored cross-site scripting vulnerability in Edit Comment. If crafted input is stored by an attacker, arbitrary script may be executed on a logged-in user's web browser. Note that Movable Type 7 series and 8.4 series, which are End-of-Life (EOL), are affected by the vulnerability as well.

CVSS v3 5.4 MEDIUM

5.4^/10

CVSS v3 : MEDIUM

Vector : AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Exploitability : 2.3 / Impact : 2.7

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required LOW

User Interaction REQUIRED

Confidentiality Impact LOW

Integrity Impact LOW

Availability Impact NONE

Scope CHANGED

References

Link	Resource
https://jvn.jp/en/jp/JVN45405689/
https://movabletype.org/news/2026/02/mt-906-released.html
https://www.sixapart.jp/movabletype/news/2026/02/04-1100.html

Configurations

No configuration.

History

No history.

Information

Published : 2026-02-04 07:16

Updated : 2026-06-17 10:18

NVD link : CVE-2026-21393

Mitre link : CVE-2026-21393

CVE.ORG link : CVE-2026-21393

JSON object : View

Products Affected

No product.

CWE

CWE-79

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

{"id": "CVE-2026-21393", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-21393", "role": "CISA Coordinator", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "version": "2.0.3", "timestamp": "2026-02-04T16:08:19.248184Z"}}], "cvssMetricV30": [{"type": "Secondary", "source": "vultures@jpcert.or.jp", "cvssData": {"scope": "CHANGED", "version": "3.0", "baseScore": 5.4, "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N", "integrityImpact": "LOW", "userInteraction": "REQUIRED", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "LOW", "confidentialityImpact": "LOW"}, "impactScore": 2.7, "exploitabilityScore": 2.3}], "cvssMetricV40": [{"type": "Secondary", "source": "vultures@jpcert.or.jp", "cvssData": {"Safety": "NOT_DEFINED", "version": "4.0", "Recovery": "NOT_DEFINED", "baseScore": 4.8, "Automatable": "NOT_DEFINED", "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "exploitMaturity": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED", "userInteraction": "ACTIVE", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "LOW", "subIntegrityImpact": "LOW", "vulnIntegrityImpact": "NONE", "integrityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "vulnAvailabilityImpact": "NONE", "availabilityRequirement": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "subConfidentialityImpact": "LOW", "vulnConfidentialityImpact": "NONE", "confidentialityRequirement": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED"}}]}, "affected": [{"source": "vultures@jpcert.or.jp", "affectedData": [{"vendor": "Six Apart Ltd.", "product": "Movable Type (Software Edition)", "versions": [{"status": "affected", "version": "9.0.4 to 9.0.5 (9.0 series)"}, {"status": "affected", "version": "8.8.0 to 8.8.1 (8.8 series)"}, {"status": "affected", "version": "8.0.2 to 8.0.8 (8.0 series)"}]}, {"vendor": "Six Apart Ltd.", "product": "Movable Type Advanced (Software Edition)", "versions": [{"status": "affected", "version": "9.0.4 to 9.0.5 (9.0 series)"}, {"status": "affected", "version": "8.8.0 to 8.8.1 (8.8 series)"}, {"status": "affected", "version": "8.0.2 to 8.0.8 (8.0 series)"}]}, {"vendor": "Six Apart Ltd.", "product": "Movable Type Premium (Software Edition)", "versions": [{"status": "affected", "version": "9.0.4 (MTP 9.0 series)"}, {"status": "affected", "version": "2.13 and earlier (MTP 2 series)"}]}, {"vendor": "Six Apart Ltd.", "product": "Movable Type Premium (Advanced Edition) (Software Edition)", "versions": [{"status": "affected", "version": "9.0.4 (MTP 9.0 series)"}, {"status": "affected", "version": "2.13 and earlier (MTP 2 series)"}]}, {"vendor": "Six Apart Ltd.", "product": "Movable Type (Cloud Edition)", "versions": [{"status": "affected", "version": "9.0.5 (9 series)"}, {"status": "affected", "version": "8.8.1 (8 series)"}]}, {"vendor": "Six Apart Ltd.", "product": "Movable Type Premium (Cloud Edition)", "versions": [{"status": "affected", "version": "9.0.5 (9 series)"}, {"status": "affected", "version": "2.12 (MTP 2 series)"}]}]}], "published": "2026-02-04T07:16:01.027", "references": [{"url": "https://jvn.jp/en/jp/JVN45405689/", "source": "vultures@jpcert.or.jp"}, {"url": "https://movabletype.org/news/2026/02/mt-906-released.html", "source": "vultures@jpcert.or.jp"}, {"url": "https://www.sixapart.jp/movabletype/news/2026/02/04-1100.html", "source": "vultures@jpcert.or.jp"}], "vulnStatus": "Deferred", "weaknesses": [{"type": "Secondary", "source": "vultures@jpcert.or.jp", "description": [{"lang": "en", "value": "CWE-79"}]}], "descriptions": [{"lang": "en", "value": "Movable Type contains a stored cross-site scripting vulnerability in Edit Comment. If crafted input is stored by an attacker, arbitrary script may be executed on a logged-in user's web browser. Note that Movable Type 7 series and 8.4 series, which are End-of-Life (EOL), are affected by the vulnerability as well."}, {"lang": "es", "value": "Movable Type contiene una vulnerabilidad de cross-site scripting almacenado en Edit Comment. Si una entrada manipulada es almacenada por un atacante, se puede ejecutar script arbitrario en el navegador web de un usuario que ha iniciado sesi\u00f3n. Tenga en cuenta que las series Movable Type 7 y 8.4, que est\u00e1n al final de su vida \u00fatil (EOL), tambi\u00e9n se ven afectadas por la vulnerabilidad."}], "lastModified": "2026-06-17T10:18:37.133", "sourceIdentifier": "vultures@jpcert.or.jp"}