{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-5388",
        "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
        "state": "PUBLISHED",
        "assignerShortName": "VulnCheck",
        "dateReserved": "2026-04-01T21:11:10.753Z",
        "datePublished": "2026-08-23T13:34:09.169Z",
        "dateUpdated": "2026-08-23T13:34:09.169Z"
    },
    "containers": {
        "cna": {
            "providerMetadata": {
                "orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
                "shortName": "VulnCheck",
                "dateUpdated": "2026-08-23T13:34:09.169Z"
            },
            "datePublic": "2026-04-09T00:00:00.000Z",
            "title": "justhtml before 1.15.0 Multiple Security Issues",
            "descriptions": [
                {
                    "lang": "en",
                    "value": "justhtml before 1.15.0 contains multiple security issues in URL sanitization helpers (clean_url_value/clean_url_in_js_string), HTML serialization, Markdown passthrough (html_passthrough=True), and several custom sanitization-policy edge cases. Depending on configuration, an attacker can bypass sanitization to inject active HTML and JavaScript — for example via encoded javascript: URLs, backslash-based relative URLs resolved as remote hosts, markup-breaking programmatic element/attribute names or HTML comments, raw </textarea> reintroduction through Markdown passthrough, or preserved <style>/<meta http-equiv=refresh>/<base href> tags in custom policies. Most custom-policy issues do not affect the default sanitize=True configuration; they primarily affect helper APIs, programmatic DOM construction, html_passthrough=True, and custom policies/transform pipelines."
                }
            ],
            "problemTypes": [
                {
                    "descriptions": [
                        {
                            "lang": "en",
                            "description": "Improper Input Validation",
                            "cweId": "CWE-20",
                            "type": "CWE"
                        }
                    ]
                }
            ],
            "affected": [
                {
                    "vendor": "EmilStenstrom",
                    "product": "justhtml",
                    "defaultStatus": "unaffected",
                    "packageURL": "pkg:pypi/justhtml",
                    "versions": [
                        {
                            "version": "0",
                            "status": "affected",
                            "versionType": "semver",
                            "lessThan": "1.15.0"
                        },
                        {
                            "version": "1.15.0",
                            "status": "unaffected",
                            "versionType": "semver"
                        }
                    ]
                }
            ],
            "metrics": [
                {
                    "cvssV4_0": {
                        "Automatable": "NOT_DEFINED",
                        "Recovery": "NOT_DEFINED",
                        "Safety": "NOT_DEFINED",
                        "attackComplexity": "LOW",
                        "attackRequirements": "NONE",
                        "attackVector": "NETWORK",
                        "baseScore": 9.3,
                        "baseSeverity": "CRITICAL",
                        "exploitMaturity": "NOT_DEFINED",
                        "privilegesRequired": "NONE",
                        "providerUrgency": "NOT_DEFINED",
                        "subAvailabilityImpact": "NONE",
                        "subConfidentialityImpact": "NONE",
                        "subIntegrityImpact": "NONE",
                        "userInteraction": "NONE",
                        "valueDensity": "NOT_DEFINED",
                        "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N",
                        "version": "4.0",
                        "vulnAvailabilityImpact": "HIGH",
                        "vulnConfidentialityImpact": "HIGH",
                        "vulnIntegrityImpact": "HIGH",
                        "vulnerabilityResponseEffort": "NOT_DEFINED"
                    },
                    "format": "CVSS"
                },
                {
                    "cvssV3_1": {
                        "attackComplexity": "LOW",
                        "attackVector": "NETWORK",
                        "availabilityImpact": "HIGH",
                        "baseScore": 9.8,
                        "baseSeverity": "CRITICAL",
                        "confidentialityImpact": "HIGH",
                        "integrityImpact": "HIGH",
                        "privilegesRequired": "NONE",
                        "scope": "UNCHANGED",
                        "userInteraction": "NONE",
                        "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
                        "version": "3.1"
                    },
                    "format": "CVSS"
                }
            ],
            "references": [
                {
                    "url": "https://github.com/EmilStenstrom/justhtml/security/advisories/GHSA-c9vm-hv86-f23r",
                    "tags": [
                        "vendor-advisory"
                    ],
                    "name": "GitHub Security Advisory (GHSA-c9vm-hv86-f23r)"
                },
                {
                    "name": "VulnCheck Advisory: justhtml before 1.15.0 Multiple Security Issues",
                    "tags": [
                        "third-party-advisory"
                    ],
                    "url": "https://www.vulncheck.com/advisories/justhtml-before-multiple-security-issues"
                }
            ],
            "credits": [
                {
                    "lang": "en",
                    "value": "EmilStenstrom",
                    "type": "coordinator"
                }
            ],
            "x_generator": {
                "engine": "vulncheck-endgame"
            }
        }
    }
}