GHSA-5QR2-V392-M9G8

Vulnerability from github – Published: 2026-09-08 17:58 – Updated: 2026-09-08 17:58
VLAI
Summary
SWC HTML minifier may allow script element breakout when minifying embedded JSON
Details

Impact

@swc/html minifies JSON contained in script elements such as application/json and application/ld+json by parsing and serializing the JSON value.

Before the patched versions, JSON serialization could convert escaped less-than signs such as \u003C into literal < characters. If the JSON contained an escaped </script> sequence, the generated HTML could terminate the containing script element early because HTML tokenization occurs before the JSON is consumed.

Applications that minify HTML containing attacker-controlled JSON data could therefore transform inert data into active markup. A crafted payload could execute script in the origin of the generated page.

Patches

The issue is fixed in:

  • @swc/html 1.15.47
  • swc_html_minifier 59.0.0

The minifier now re-escapes less-than signs after JSON serialization, preserving the script element boundary.

Workarounds

Users who cannot upgrade can disable JSON minification with:

```js await minify(html, { minifyJson: false, });

Severity
6.1 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "@swc/html"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.15.47-nightly-20260729.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "crates.io",
        "name": "swc_html_minifier"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "59.0.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-72925"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-116",
      "CWE-79"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-08T17:58:00Z",
    "nvd_published_at": "2026-08-11T15:17:38Z",
    "severity": "MODERATE"
  },
  "details": "## Impact\n\n`@swc/html` minifies JSON contained in `script` elements such as\n`application/json` and `application/ld+json` by parsing and serializing the\nJSON value.\n\nBefore the patched versions, JSON serialization could convert escaped\nless-than signs such as `\\u003C` into literal `\u003c` characters. If the JSON\ncontained an escaped `\u003c/script\u003e` sequence, the generated HTML could terminate\nthe containing script element early because HTML tokenization occurs before\nthe JSON is consumed.\n\nApplications that minify HTML containing attacker-controlled JSON data could\ntherefore transform inert data into active markup. A crafted payload could\nexecute script in the origin of the generated page.\n\n## Patches\n\nThe issue is fixed in:\n\n- `@swc/html` 1.15.47\n- `swc_html_minifier` 59.0.0\n\nThe minifier now re-escapes less-than signs after JSON serialization, preserving\nthe script element boundary.\n\n## Workarounds\n\nUsers who cannot upgrade can disable JSON minification with:\n\n```js\nawait minify(html, {\n  minifyJson: false,\n});",
  "id": "GHSA-5qr2-v392-m9g8",
  "modified": "2026-09-08T17:58:00Z",
  "published": "2026-09-08T17:58:00Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/swc-project/swc/security/advisories/GHSA-5qr2-v392-m9g8"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-72925"
    },
    {
      "type": "WEB",
      "url": "https://github.com/swc-project/swc/pull/12080"
    },
    {
      "type": "WEB",
      "url": "https://github.com/swc-project/swc/commit/e1877b44bdac8abc9fd51e984d584f40f6999832"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/swc-project/swc"
    },
    {
      "type": "WEB",
      "url": "https://github.com/swc-project/swc/releases/tag/v1.15.47"
    },
    {
      "type": "WEB",
      "url": "https://github.com/swc-project/swc/releases/tag/v1.15.47-nightly-20260729.1"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "SWC HTML minifier may allow script element breakout when minifying embedded JSON"
}



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