SvelteKit : XSS via untrusted cache-control header in prerendered page

{
  "id": "058729b9d1a31e85555b6e2f8696473e37093b4da4aa0eebaa45c2635ba53ef5",
  "url": "https://osv.dev/vulnerability/GHSA-27mw-82g8-phjj",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "SvelteKit : XSS via untrusted cache-control header in prerendered page",
    "summary": "### Impact Applications that prerender pages and use `setHeaders` to set a `cache-control` header from an untrusted source are vulnerable to cross-site scripting (XSS). SvelteKit inserts the header value into a `` tag without escaping it. An attacker who can influence this value at prerender time can break out of the `content` attribute and inject HTML or JavaScript into the generated page. The injected code can then execute when users visit the page. ### Patches The fix escapes the header value before inserting it into the generated HTML. Upgrade to `@sveltejs/kit` version 3.0.0 or later. ### Workarounds Avoid forwarding untrusted `cache-control` header values with `setHeaders` on prerendered pages. Use a fixed, trusted cache policy instead.",
    "evidence": "osv:GHSA-27mw-82g8-phjj",
    "products": [
      {
        "name": {
          "value": "@sveltejs/kit",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "3.0.0",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "low",
    "structured": {
      "id": "GHSA-27mw-82g8-phjj",
      "aliases": [
        "CVE-2026-114061",
        "GHSA-27mw-82g8-phjj"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "3.0.0"
                }
              ]
            }
          ],
          "package": {
            "name": "@sveltejs/kit",
            "purl": "pkg:npm/%40sveltejs/kit",
            "ecosystem": "npm"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-27mw-82g8-phjj/GHSA-27mw-82g8-phjj.json"
          }
        }
      ],
      "modified": "2026-10-23T21:00:04.312966515Z",
      "provider": "osv",
      "references": [
        "https://github.com/sveltejs/kit/security/advisories/GHSA-27mw-82g8-phjj",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-114061",
        "https://github.com/sveltejs/kit/commit/d9d55b579743c80ee7cb59c272d864fd9253dae7",
        "https://github.com/sveltejs/kit",
        "https://github.com/sveltejs/kit/releases/tag/@sveltejs/kit@3.0.0",
        "https://www.vulncheck.com/advisories/sveltekit-before-3.0.0-xss-via-cache-control-header-in-prerendered-pages"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-79"
        ],
        "severity": "LOW",
        "github_reviewed": true,
        "nvd_published_at": null,
        "github_reviewed_at": "2026-10-23T20:43:30Z"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-114061",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/database_specific/severity"
  },
  "source_id": "core-osv",
  "document_id": 427020,
  "published_at": "2026-10-23T20:43:30+00:00"
}