CVE-2026-31859

Craft is a content management system (CMS). The fix for CVE-2025-35939 in craftcms/cms introduced a strip_tags() call in src/web/User.php to sanitize return URLs before they are stored in the session. However, strip_tags() only removes HTML tags (angle brackets) -- it does not inspect or filter URL schemes. Payloads like javascript:alert(document.cookie) contain no HTML tags and pass through strip_tags() completely unmodified, enabling reflected XSS when the return URL is rendered in an href attribute. This vulnerability is fixed in 5.9.7 and 4.17.3.

CVSS v3 6.1 MEDIUM

6.1^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.8 / Impact : 2.7

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction REQUIRED

Confidentiality Impact LOW

Integrity Impact LOW

Availability Impact NONE

Scope CHANGED

References

Link	Resource
https://github.com/craftcms/cms/security/advisories/GHSA-fvwq-45qv-xvhv	Patch Vendor Advisory

Configurations

Configuration 1 (hide)

OR	cpe:2.3:a:craftcms:craft_cms::::::::
	cpe:2.3:a:craftcms:craft_cms::::::::

History

No history.

Information

Published : 2026-03-11 18:16

Updated : 2026-03-17 14:03

NVD link : CVE-2026-31859

Mitre link : CVE-2026-31859

CVE.ORG link : CVE-2026-31859

JSON object : View

Products Affected

craftcms

craft_cms

CWE

CWE-79

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

CWE-116

Improper Encoding or Escaping of Output

{"id": "CVE-2026-31859", "cveTags": [], "metrics": {"cvssMetricV31": [{"type": "Primary", "source": "nvd@nist.gov", "cvssData": {"scope": "CHANGED", "version": "3.1", "baseScore": 6.1, "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N", "integrityImpact": "LOW", "userInteraction": "REQUIRED", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "NONE", "confidentialityImpact": "LOW"}, "impactScore": 2.7, "exploitabilityScore": 2.8}], "cvssMetricV40": [{"type": "Secondary", "source": "security-advisories@github.com", "cvssData": {"Safety": "NOT_DEFINED", "version": "4.0", "Recovery": "NOT_DEFINED", "baseScore": 6.9, "Automatable": "NOT_DEFINED", "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/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": "NONE", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "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"}}]}, "published": "2026-03-11T18:16:24.710", "references": [{"url": "https://github.com/craftcms/cms/security/advisories/GHSA-fvwq-45qv-xvhv", "tags": ["Patch", "Vendor Advisory"], "source": "security-advisories@github.com"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Primary", "source": "security-advisories@github.com", "description": [{"lang": "en", "value": "CWE-79"}, {"lang": "en", "value": "CWE-116"}]}], "descriptions": [{"lang": "en", "value": "Craft is a content management system (CMS). The fix for CVE-2025-35939 in craftcms/cms introduced a strip_tags() call in src/web/User.php to sanitize return URLs before they are stored in the session. However, strip_tags() only removes HTML tags (angle brackets) -- it does not inspect or filter URL schemes. Payloads like javascript:alert(document.cookie) contain no HTML tags and pass through strip_tags() completely unmodified, enabling reflected XSS when the return URL is rendered in an href attribute. This vulnerability is fixed in 5.9.7 and 4.17.3."}, {"lang": "es", "value": "Craft es un sistema de gesti\u00f3n de contenidos (CMS). La correcci\u00f3n para CVE-2025-35939 en craftcms/cms introdujo una llamada a strip_tags() en src/web/User.php para depurar las URL de retorno antes de que se almacenen en la sesi\u00f3n. Sin embargo, strip_tags() solo elimina las etiquetas HTML (corchetes angulares); no inspecciona ni filtra los esquemas de URL. Las cargas \u00fatiles como javascript:alert(document.cookie) no contienen etiquetas HTML y pasan por strip_tags() sin sufrir ninguna modificaci\u00f3n, lo que permite un XSS reflejado cuando la URL de retorno se representa en un atributo href. Esta vulnerabilidad se ha corregido en las versiones 5.9.7 y 4.17.3."}], "lastModified": "2026-03-17T14:03:57.187", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:craftcms:craft_cms:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "4634EACF-27D5-4F3E-8314-9E02BB40E83F", "versionEndExcluding": "4.17.3", "versionStartIncluding": "4.15.3"}, {"criteria": "cpe:2.3:a:craftcms:craft_cms:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "B6802B26-EF36-4A1A-A589-DC92FBCE4D85", "versionEndExcluding": "5.9.7", "versionStartIncluding": "5.7.5"}], "operator": "OR"}]}], "sourceIdentifier": "security-advisories@github.com"}