CVE-2026-31868: Parse server Cross-Site Scripting Vulnerability

MODERATE
Advisory Identifier: GHSA-v5hf-f4c3-m5rv
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CWE-79
Published
Advisory Summary

CVE-2026-31868 is a MODERATE 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 xss via file upload of html-renderable file types. Remediation is available by upgrading affected packages to version 9.6.0-alpha.4, 8.6.30.

CVE-2026-31868 at a Glance

CVE Identifier CVE-2026-31868
GHSA Identifier GHSA-v5hf-f4c3-m5rv
Severity MODERATE
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-2026-31868

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: 9.6.0-alpha.4 
npm install parse-server@9.6.0-alpha.4
parse-server fixed: 8.6.30 
npm install parse-server@8.6.30
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-2026-31868, 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 9.6.0-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 An attacker can upload a file with a file extension or content type that is not blocked by the default configuration of the Parse Server `fileUpload.fileExtensions` option. The file can contain malicious code, for example JavaScript in an SVG or XHTML file. When the file is accessed via its URL, the browser renders the file and executes the malicious code in the context of the Parse Server domain. This is a stored Cross-Site Scripting (XSS) vulnerability that can be exploited to steal session tokens, redirect users, or perform actions on behalf of other users. Affected file extensions and content types include `.svgz`, `.xht`, `.xml`, `.xsl`, `.xslt`, and content types `application/xhtml+xml` and `application/xslt+xml` for extensionless uploads. Uploading of `.html`, `.htm`, `.shtml`, `.xhtml`, and `.svg` files was already blocked. ### Patches The fix adds the missing file extensions and content types to the default value of the `fileUpload.fileExtensions` server option. ### Workarounds Configure the `fileUpload.fileExtensions` server option to block the affected file extensions and content types. ### References - GitHub security advisory: https://github.com/parse-community/parse-server/security/advisories/GHSA-v5hf-f4c3-m5rv - Fix Parse Server 9: https://github.com/parse-community/parse-server/releases/tag/9.6.0-alpha.4 - Fix Parse Server 8: https://github.com/parse-community/parse-server/releases/tag/8.6.30

CVE-2026-31868 Affected Parse server Versions

2 component(s)
Fixed Versions:
9.6.0-alpha.48.6.30
Product / Package Ecosystem Affected Versions Fixed Version
parse-server
npm/parse-server
npm
≥ 9.0.0-alpha.1
< 9.6.0-alpha.4
9.6.0-alpha.4
parse-server
npm/parse-server
npm
< 8.6.30
8.6.30

References

GitHub Advisory / Wiki ADVISORY
https://github.com/parse-community/parse-server/security/advisories/GHSA-v5hf-f4c3-m5rv
NVD — CVE-2026-31868 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-31868
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/8.6.30
Parse server Release RELEASE
https://github.com/parse-community/parse-server/releases/tag/9.6.0-alpha.4

Frequently Asked Questions

What is CVE-2026-31868?
CVE-2026-31868 is a security vulnerability in Parse server involving Parse Server vulnerable to stored XSS via file upload of HTML-renderable file types 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 9.6.0-alpha.4, 8.6.30 across affected packages: parse-server.
What version fixes CVE-2026-31868?
Upgrading to 9.6.0-alpha.4, 8.6.30 (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 9.6.0-alpha.4, 8.6.30. Upgrade your dependency to 9.6.0-alpha.4, 8.6.30 or later.
What CWE is associated with CVE-2026-31868?
CVE-2026-31868 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-2026-31868?
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-v5hf-f4c3-m5rv",
  "modified" : "2026-03-11T20:57:39Z",
  "published" : "2026-03-11T00:34:24Z",
  "aliases" : [ "CVE-2026-31868" ],
  "summary" : "Parse Server vulnerable to stored XSS via file upload of HTML-renderable file types",
  "details" : "### Impact\n\nAn attacker can upload a file with a file extension or content type that is not blocked by the default configuration of the Parse Server `fileUpload.fileExtensions` option. The file can contain malicious code, for example JavaScript in an SVG or XHTML file. When the file is accessed via its URL, the browser renders the file and executes the malicious code in the context of the Parse Server domain. This is a stored Cross-Site Scripting (XSS) vulnerability that can be exploited to steal session tokens, redirect users, or perform actions on behalf of other users.\n\nAffected file extensions and content types include `.svgz`, `.xht`, `.xml`, `.xsl`, `.xslt`, and content types `application/xhtml+xml` and `application/xslt+xml` for extensionless uploads. Uploading of `.html`, `.htm`, `.shtml`, `.xhtml`, and `.svg` files was already blocked.\n\n### Patches\n\nThe fix adds the missing file extensions and content types to the default value of the `fileUpload.fileExtensions` server option.\n\n### Workarounds\n\nConfigure the `fileUpload.fileExtensions` server option to block the affected file extensions and content types.\n\n### References\n\n- GitHub security advisory: https://github.com/parse-community/parse-server/security/advisories/GHSA-v5hf-f4c3-m5rv\n- Fix Parse Server 9: https://github.com/parse-community/parse-server/releases/tag/9.6.0-alpha.4\n- Fix Parse Server 8: https://github.com/parse-community/parse-server/releases/tag/8.6.30",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/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-alpha.1"
      }, {
        "fixed" : "9.6.0-alpha.4"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "parse-server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "8.6.30"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/parse-community/parse-server/security/advisories/GHSA-v5hf-f4c3-m5rv"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-31868"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/parse-community/parse-server"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/parse-community/parse-server/releases/tag/8.6.30"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/parse-community/parse-server/releases/tag/9.6.0-alpha.4"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-11T00:34:24Z",
    "nvd_published_at" : "2026-03-11T18:16:25Z"
  }
}