{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "2.8.4"
              }
            ],
            "source": [
              "DESCRIPTION",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "12cf0b1f25f026a022fe728ad8f7e3d017285b80"
            },
            {
              "fixed": "ff6e1d7e750bbe245178f51a47a965dc8342861a"
            }
          ],
          "repo": "https://github.com/libexpat/libexpat",
          "type": "GIT"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "VulnCheck",
    "cwe_ids": [
      "CWE-176"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/93xxx/CVE-2026-93990.json"
  },
  "details": "Expat through 2.8.4 fails to validate low surrogates following high surrogates in UTF-16 input, allowing malformed UTF-16 sequences to be accepted. Attackers can craft UTF-16 encoded XML with lone high surrogates that consume following code units, hiding markup characters from the parser and enabling XML injection attacks.",
  "id": "CVE-2026-93990",
  "modified": "2026-09-20T11:30:37.164663881Z",
  "published": "2026-09-19T22:58:11.224Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/93xxx/CVE-2026-93990.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-93990"
    },
    {
      "type": "ADVISORY",
      "url": "https://www.vulncheck.com/advisories/expat-through-2.8.4-malformed-utf-16-acceptance-via-unchecked-surrogate"
    },
    {
      "type": "FIX",
      "url": "https://github.com/libexpat/libexpat/commit/ff6e1d7e750bbe245178f51a47a965dc8342861a"
    },
    {
      "type": "FIX",
      "url": "https://github.com/libexpat/libexpat/pull/1282"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/libexpat/libexpat"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Expat through 2.8.4 Malformed UTF-16 Acceptance via Unchecked Surrogate"
}