CVE-2026-30948: Parse server Cross-Site Scripting Vulnerability

HIGH
Advisory Identifier: GHSA-hcj7-6gxh-24ww
Share
CWE-79
Published
Advisory Summary

CVE-2026-30948 is a HIGH cross-site scripting vulnerability (CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) affecting Parse server libraries in the npm ecosystem. The issue involves parse server vulnerable to stored cross-site scripting (xss) via svg file upload. Remediation is available by upgrading affected packages to version 9.5.2-alpha.4, 8.6.17.

CVE-2026-30948 at a Glance

CVE Identifier CVE-2026-30948
GHSA Identifier GHSA-hcj7-6gxh-24ww
Severity HIGH
CVSS v3.1 Base Score N/A
CWE Classification CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Product Parse server
Package Ecosystem npm
Published Date
Last Updated

How to Fix CVE-2026-30948

To remediate this vulnerability, upgrade all affected Parse server dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

parse-server fixed: 9.5.2-alpha.4 
npm install parse-server@9.5.2-alpha.4
parse-server fixed: 8.6.17 
npm install parse-server@8.6.17
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls parse-server

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-30948, inspect your project dependencies using npm:

npm ls parse-server

Analyze the terminal output to locate any version of Parse server in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 9.5.2-alpha.4), your application is affected.

Note: The npm ls parse-server command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'), where the product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. In Parse server, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### 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: ```js { 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

CVE-2026-30948 Affected Parse server Versions

2 component(s)
Fixed Versions:
9.5.2-alpha.48.6.17
Product / Package Ecosystem Affected Versions Fixed Version
parse-server
npm/parse-server
npm
≥ 9.0.0
< 9.5.2-alpha.4
9.5.2-alpha.4
parse-server
npm/parse-server
npm
< 8.6.17
8.6.17

References

GitHub Advisory / Wiki ADVISORY
https://github.com/parse-community/parse-server/security/advisories/GHSA-hcj7-6gxh-24ww
NVD — CVE-2026-30948 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-30948
Parse server Source Repository REPOSITORY
https://github.com/parse-community/parse-server
Parse server Release RELEASE
https://github.com/parse-community/parse-server/releases/tag/8.6.17
Parse server Release RELEASE
https://github.com/parse-community/parse-server/releases/tag/9.5.2-alpha.4

Frequently Asked Questions

What is CVE-2026-30948?
CVE-2026-30948 is a security vulnerability in Parse server involving Parse Server vulnerable to stored cross-site scripting (XSS) via SVG file upload under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting').
Which Parse server versions are affected?
Affected versions include releases prior to 9.5.2-alpha.4, 8.6.17 across affected packages: parse-server.
What version fixes CVE-2026-30948?
Upgrading to 9.5.2-alpha.4, 8.6.17 (or the latest patched release for your respective branch) resolves the vulnerability.
Is parse-server affected?
Yes, parse-server is affected in releases prior to 9.5.2-alpha.4, 8.6.17. Upgrade your dependency to 9.5.2-alpha.4, 8.6.17 or later.
What CWE is associated with CVE-2026-30948?
CVE-2026-30948 is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.).
How can I check npm dependencies for CVE-2026-30948?
Run the dependency tree command: 'npm ls parse-server'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-hcj7-6gxh-24ww",
  "modified" : "2026-03-11T00:17:35Z",
  "published" : "2026-03-11T00:17:35Z",
  "aliases" : [ "CVE-2026-30948" ],
  "summary" : "Parse Server vulnerable to stored cross-site scripting (XSS) via SVG file upload",
  "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: ['^(?!([xXsS]?[hH][tT][mM][lL]?|[sS][vV][gG])$)']\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",
  "severity" : [ {
    "type" : "CVSS_V4",
    "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"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "parse-server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "9.0.0"
      }, {
        "fixed" : "9.5.2-alpha.4"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "parse-server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "8.6.17"
      } ]
    } ]
  } ],
  "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"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-11T00:17:35Z",
    "nvd_published_at" : "2026-03-10T21:16:47Z"
  }
}