CVE-2026-3495

Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13 fail to escape some variables that could contain malicious content during error page composition which allows an attacker with access to edit some site configuration to execute some malicious code via injecting some JS as part of those values.. Mattermost Advisory ID: MMSA-2026-00622

CVSS v3 3.8 LOW

3.8^/10

CVSS v3 : LOW

Vector :

Exploitability : 1.2 / Impact : 2.5

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required HIGH

User Interaction NONE

Confidentiality Impact LOW

Integrity Impact LOW

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://mattermost.com/security-updates	Vendor Advisory

Configurations

Configuration 1 (hide)

OR	cpe:2.3:a:mattermost:mattermost_server::::::::
	cpe:2.3:a:mattermost:mattermost_server::::::::

History

14 Oct 2026, 20:10

Type	Values Removed	Values Added
Summary		(es) Mattermost versiones 11.5.x menor o igual que 11.5.1, 10.11.x menor o igual que 10.11.13 no escapan algunas variables que podrían contener contenido malicioso durante la composición de la página de error, lo que permite a un atacante con acceso para editar alguna configuración del sitio ejecutar código malicioso mediante la inyección de JS como parte de esos valores. ID de Aviso de Mattermost: MMSA-2026-00622

Information

Published : 2026-05-18 08:16

Updated : 2026-10-14 20:10

NVD link : CVE-2026-3495

Mitre link : CVE-2026-3495

CVE.ORG link : CVE-2026-3495

JSON object : View

Products Affected

mattermost

mattermost_server

CWE

CWE-79

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

{"id": "CVE-2026-3495", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-3495", "role": "CISA Coordinator", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "version": "2.0.3", "timestamp": "2026-05-18T14:33:19.230906Z"}}], "cvssMetricV31": [{"type": "Secondary", "source": "responsibledisclosure@mattermost.com", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 3.8, "attackVector": "NETWORK", "baseSeverity": "LOW", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:N", "integrityImpact": "LOW", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "HIGH", "confidentialityImpact": "LOW"}, "impactScore": 2.5, "exploitabilityScore": 1.2}, {"type": "Primary", "source": "nvd@nist.gov", "cvssData": {"scope": "CHANGED", "version": "3.1", "baseScore": 4.8, "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N", "integrityImpact": "LOW", "userInteraction": "REQUIRED", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "HIGH", "confidentialityImpact": "LOW"}, "impactScore": 2.7, "exploitabilityScore": 1.7}]}, "affected": [{"source": "responsibledisclosure@mattermost.com", "affectedData": [{"vendor": "Mattermost", "product": "Mattermost", "versions": [{"status": "affected", "version": "11.5.0", "versionType": "semver", "lessThanOrEqual": "11.5.1"}, {"status": "affected", "version": "10.11.0", "versionType": "semver", "lessThanOrEqual": "10.11.13"}, {"status": "unaffected", "version": "11.6.0"}, {"status": "unaffected", "version": "11.5.2"}, {"status": "unaffected", "version": "10.11.14"}], "defaultStatus": "unaffected"}]}], "published": "2026-05-18T08:16:13.900", "references": [{"url": "https://mattermost.com/security-updates", "tags": ["Vendor Advisory"], "source": "responsibledisclosure@mattermost.com"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Secondary", "source": "responsibledisclosure@mattermost.com", "description": [{"lang": "en", "value": "CWE-79"}]}], "descriptions": [{"lang": "en", "value": "Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13 fail to escape some variables that could contain malicious content during error page composition which allows an attacker with access to edit some site configuration to execute some malicious code via injecting some JS as part of those values.. Mattermost Advisory ID: MMSA-2026-00622"}, {"lang": "es", "value": "Mattermost versiones 11.5.x menor o igual que 11.5.1, 10.11.x menor o igual que 10.11.13 no escapan algunas variables que podr\u00edan contener contenido malicioso durante la composici\u00f3n de la p\u00e1gina de error, lo que permite a un atacante con acceso para editar alguna configuraci\u00f3n del sitio ejecutar c\u00f3digo malicioso mediante la inyecci\u00f3n de JS como parte de esos valores. ID de Aviso de Mattermost: MMSA-2026-00622"}], "lastModified": "2026-10-14T20:10:00.190", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "413D9405-79C3-4299-B0DC-40D9EE5CC717", "versionEndExcluding": "10.11.14", "versionStartIncluding": "10.11.0"}, {"criteria": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "726AD6AD-6C01-45BB-9115-B8209717A6D4", "versionEndExcluding": "11.5.2", "versionStartIncluding": "11.5.0"}], "operator": "OR"}]}], "sourceIdentifier": "responsibledisclosure@mattermost.com"}