GHSA-HCJ7-6GXH-24WW

Vulnerability from github – Published: 2026-03-11 00:17 – Updated: 2026-03-11 00:17
VLAI?
Summary
Parse Server vulnerable to stored cross-site scripting (XSS) via SVG file upload
Details

Impact

A stored cross-site scripting (XSS) vulnerability allows any authenticated user to upload an SVG file containing JavaScript. The file is served inline with Content-Type: image/svg+xml and without protective headers, causing the browser to execute embedded scripts in the Parse Server origin. This can be exploited to steal session tokens from localStorage and achieve account takeover.

The default fileExtensions option blocks HTML file extensions but does not block SVG, which is a well-known XSS vector. All Parse Server deployments where file upload is enabled for authenticated users (the default) are affected.

Patches

The fix adds svg (case-insensitive) to the default file extension denylist. The default regex changes from ^(?![xXsS]?[hH][tT][mM][lL]?$) to ^(?!([xXsS]?[hH][tT][mM][lL]?|[sS][vV][gG])$).

Workarounds

Configure the fileExtensions option to explicitly block SVG uploads:

{
  fileUpload: {
    fileExtensions: ['^(?!([xXsS]?[hH][tT][mM][lL]?|[sS][vV][gG])$)']
  }
}

References

  • GitHub security advisory: https://github.com/parse-community/parse-server/security/advisories/GHSA-hcj7-6gxh-24ww
  • Fix Parse Server 9: https://github.com/parse-community/parse-server/releases/tag/9.5.2-alpha.4
  • Fix Parse Server 8: https://github.com/parse-community/parse-server/releases/tag/8.6.17
Severity ?
8.3 (High)
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:N/VA:N/SC:H/SI:H/SA:N
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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "parse-server"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "9.0.0"
            },
            {
              "fixed": "9.5.2-alpha.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "npm",
        "name": "parse-server"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "8.6.17"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-30948"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-79"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-11T00:17:35Z",
    "nvd_published_at": "2026-03-10T21:16:47Z",
    "severity": "HIGH"
  },
  "details": "### Impact\n\nA stored cross-site scripting (XSS) vulnerability allows any authenticated user to upload an SVG file containing JavaScript. The file is served inline with `Content-Type: image/svg+xml` and without protective headers, causing the browser to execute embedded scripts in the Parse Server origin. This can be exploited to steal session tokens from `localStorage` and achieve account takeover.\n\nThe default `fileExtensions` option blocks HTML file extensions but does not block SVG, which is a well-known XSS vector. All Parse Server deployments where file upload is enabled for authenticated users (the default) are affected.\n\n### Patches\n\nThe fix adds `svg` (case-insensitive) to the default file extension denylist. The default regex changes from `^(?![xXsS]?[hH][tT][mM][lL]?$)` to `^(?!([xXsS]?[hH][tT][mM][lL]?|[sS][vV][gG])$)`.\n\n### Workarounds\n\nConfigure the `fileExtensions` option to explicitly block SVG uploads:\n\n```js\n{\n  fileUpload: {\n    fileExtensions: [\u0027^(?!([xXsS]?[hH][tT][mM][lL]?|[sS][vV][gG])$)\u0027]\n  }\n}\n```\n\n### References\n\n- GitHub security advisory: https://github.com/parse-community/parse-server/security/advisories/GHSA-hcj7-6gxh-24ww\n- Fix Parse Server 9: https://github.com/parse-community/parse-server/releases/tag/9.5.2-alpha.4\n- Fix Parse Server 8: https://github.com/parse-community/parse-server/releases/tag/8.6.17",
  "id": "GHSA-hcj7-6gxh-24ww",
  "modified": "2026-03-11T00:17:35Z",
  "published": "2026-03-11T00:17:35Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/parse-community/parse-server/security/advisories/GHSA-hcj7-6gxh-24ww"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-30948"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/parse-community/parse-server"
    },
    {
      "type": "WEB",
      "url": "https://github.com/parse-community/parse-server/releases/tag/8.6.17"
    },
    {
      "type": "WEB",
      "url": "https://github.com/parse-community/parse-server/releases/tag/9.5.2-alpha.4"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:N/VA:N/SC:H/SI:H/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Parse Server vulnerable to stored cross-site scripting (XSS) via SVG file upload"
}


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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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