LeafKit's HTML escaping may be skipped for Collection values, enabling XSS

{
  "id": "5ef57bfb3c3a9409208605590e9388f71a50966adc752cafc11091f29c2f065e",
  "url": "https://osv.dev/vulnerability/CVE-2026-28499",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "LeafKit's HTML escaping may be skipped for Collection values, enabling XSS",
    "summary": "LeafKit is a templating language with Swift-inspired syntax. Prior to version 1.14.2, HTML escaping doesn't work correctly when a template prints a collection (Array / Dictionary) via `#(value)`. This can result in XSS, allowing potentially untrusted input to be rendered unescaped. Version 1.14.2 fixes the issue.",
    "evidence": "osv:CVE-2026-28499",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-28499",
      "aliases": [
        "CVE-2026-28499",
        "GHSA-6jj5-j4j8-8473"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/vapor/leaf-kit",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "6044b844caa858a0c5f2505ac166f5a057c990dc"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "1.14.2"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "fixed": "6044b844caa858a0c5f2505ac166f5a057c990dc"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "6044b844caa858a0c5f2505ac166f5a057c990dc"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "1.14.2"
                  },
                  {
                    "cpe": "cpe:2.3:a:vapor:leafkit:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "1.14.2"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "1.14.1",
            "1.14.0",
            "1.13.1",
            "1.13.0",
            "1.12.0",
            "1.11.1",
            "1.11.0",
            "1.10.6",
            "1.10.5",
            "1.10.4",
            "1.10.3",
            "1.10.2",
            "1.10.1",
            "1.10.0",
            "1.9.0",
            "1.8.0",
            "1.7.0",
            "1.6.0",
            "1.5.0",
            "1.4.0",
            "1.3.1",
            "1.3.0",
            "1.2.0",
            "1.1.0",
            "1.0.0",
            "1.0.0-zeta.1",
            "1.0.0-tau.1.1",
            "1.0.0-tau.1",
            "1.0.0-rc.1.17",
            "1.0.0-rc.1.16",
            "1.0.0-rc.1.15",
            "1.0.0-rc.1.14",
            "1.0.0-rc.1.13",
            "1.0.0-rc.1.12",
            "1.0.0-rc.1.11",
            "1.0.0-rc.1.10",
            "1.0.0-rc.1.9",
            "1.0.0-rc.1.8",
            "1.0.0-rc.1.7",
            "1.0.0-rc.1.6",
            "1.0.0-rc.1.5",
            "1.0.0-rc.1.4",
            "1.0.0-rc.1.3",
            "1.0.0-rc.1.2",
            "1.0.0-rc.1.1",
            "1.0.0-rc.1",
            "1.0.0-beta.2.2",
            "1.0.0-beta.2.1",
            "1.0.0-beta.2",
            "1.0.0-alpha.1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-28499.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:32.620242449Z",
      "provider": "osv",
      "references": [
        "https://github.com/vapor/leaf-kit/releases/tag/1.14.2",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/28xxx/CVE-2026-28499.json",
        "https://github.com/vapor/leaf-kit/security/advisories/GHSA-6jj5-j4j8-8473",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-28499",
        "https://github.com/vapor/leaf-kit/commit/6044b844caa858a0c5f2505ac166f5a057c990dc"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-116",
          "CWE-79",
          "CWE-80"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/28xxx/CVE-2026-28499.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-28499",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 499522,
  "published_at": "2026-03-18T01:19:36.122+00:00"
}