{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "1.15.0"
              }
            ],
            "source": [
              "AFFECTED_FIELD",
              "DESCRIPTION"
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "c8161901e50de91ad7e09ede7baa158181ef466e"
            }
          ],
          "repo": "https://github.com/emilstenstrom/justhtml",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-c9vm-hv86-f23r"
  ],
  "database_specific": {
    "cna_assigner": "VulnCheck",
    "cwe_ids": [
      "CWE-20"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/5xxx/CVE-2026-5388.json"
  },
  "details": "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 \u003c/textarea\u003e reintroduction through Markdown passthrough, or preserved \u003cstyle\u003e/\u003cmeta http-equiv=refresh\u003e/\u003cbase href\u003e 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.",
  "id": "CVE-2026-5388",
  "modified": "2026-08-25T03:51:21.807863637Z",
  "published": "2026-08-23T13:34:09.169Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/5xxx/CVE-2026-5388.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/EmilStenstrom/justhtml/security/advisories/GHSA-c9vm-hv86-f23r"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-5388"
    },
    {
      "type": "ADVISORY",
      "url": "https://www.vulncheck.com/advisories/justhtml-before-multiple-security-issues"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "justhtml before 1.15.0 Multiple Security Issues"
}