{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-5751",
        "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
        "state": "PUBLISHED",
        "assignerShortName": "VulnCheck",
        "dateReserved": "2026-04-07T15:54:18.686Z",
        "datePublished": "2026-08-23T13:34:10.547Z",
        "dateUpdated": "2026-08-23T13:34:10.547Z"
    },
    "containers": {
        "cna": {
            "providerMetadata": {
                "orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
                "shortName": "VulnCheck",
                "dateUpdated": "2026-08-23T13:34:10.547Z"
            },
            "datePublic": "2026-04-05T00:00:00.000Z",
            "title": "justhtml before 1.14.0 Mutation XSS via custom sanitization policies",
            "descriptions": [
                {
                    "lang": "en",
                    "value": "justhtml versions 1.13.0 and earlier contain a parser-differential / mutation cross-site scripting (mXSS) vulnerability when using a custom SanitizationPolicy that preserves foreign namespaces (e.g., drop_foreign_namespaces=False with allowlisted SVG/MathML elements or raw-text containers such as <style>). Specially crafted input can sanitize into markup that appears safe but becomes unsafe when re-parsed by a browser or another HTML parser, allowing markup injection. The default safe configuration (sanitize=True) is not affected. Fixed in 1.14.0."
                }
            ],
            "problemTypes": [
                {
                    "descriptions": [
                        {
                            "lang": "en",
                            "description": "Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')",
                            "cweId": "CWE-79",
                            "type": "CWE"
                        }
                    ]
                }
            ],
            "affected": [
                {
                    "vendor": "EmilStenstrom",
                    "product": "justhtml",
                    "defaultStatus": "unaffected",
                    "packageURL": "pkg:pypi/justhtml",
                    "versions": [
                        {
                            "version": "0",
                            "status": "affected",
                            "versionType": "semver",
                            "lessThan": "1.14.0"
                        },
                        {
                            "version": "1.14.0",
                            "status": "unaffected",
                            "versionType": "semver"
                        }
                    ]
                }
            ],
            "metrics": [
                {
                    "cvssV4_0": {
                        "Automatable": "NOT_DEFINED",
                        "Recovery": "NOT_DEFINED",
                        "Safety": "NOT_DEFINED",
                        "attackComplexity": "LOW",
                        "attackRequirements": "NONE",
                        "attackVector": "NETWORK",
                        "baseScore": 5.1,
                        "baseSeverity": "MEDIUM",
                        "exploitMaturity": "NOT_DEFINED",
                        "privilegesRequired": "NONE",
                        "providerUrgency": "NOT_DEFINED",
                        "subAvailabilityImpact": "NONE",
                        "subConfidentialityImpact": "LOW",
                        "subIntegrityImpact": "LOW",
                        "userInteraction": "ACTIVE",
                        "valueDensity": "NOT_DEFINED",
                        "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N",
                        "version": "4.0",
                        "vulnAvailabilityImpact": "NONE",
                        "vulnConfidentialityImpact": "NONE",
                        "vulnIntegrityImpact": "NONE",
                        "vulnerabilityResponseEffort": "NOT_DEFINED"
                    },
                    "format": "CVSS"
                },
                {
                    "cvssV3_1": {
                        "attackComplexity": "LOW",
                        "attackVector": "NETWORK",
                        "availabilityImpact": "NONE",
                        "baseScore": 6.1,
                        "baseSeverity": "MEDIUM",
                        "confidentialityImpact": "LOW",
                        "integrityImpact": "LOW",
                        "privilegesRequired": "NONE",
                        "scope": "CHANGED",
                        "userInteraction": "REQUIRED",
                        "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
                        "version": "3.1"
                    },
                    "format": "CVSS"
                }
            ],
            "references": [
                {
                    "url": "https://github.com/EmilStenstrom/justhtml/security/advisories/GHSA-r758-8hxw-4845",
                    "tags": [
                        "vendor-advisory"
                    ],
                    "name": "GitHub Security Advisory (GHSA-r758-8hxw-4845)"
                },
                {
                    "name": "VulnCheck Advisory: justhtml before 1.14.0 Mutation XSS via custom sanitization policies",
                    "tags": [
                        "third-party-advisory"
                    ],
                    "url": "https://www.vulncheck.com/advisories/justhtml-before-mutation-xss-via-custom-sanitization-policies"
                }
            ],
            "credits": [
                {
                    "lang": "en",
                    "value": "EmilStenstrom",
                    "type": "coordinator"
                }
            ],
            "x_generator": {
                "engine": "vulncheck-endgame"
            }
        }
    }
}