CVE-2026-49252: @deepstream/server Deepstream Is Vulnerable To Prototype Vulnerability

CRITICAL
Advisory Identifier: GHSA-9v98-6g37-x9g6
Share
CVSS 9.9
CWE-1321
Published
Advisory Summary

CVE-2026-49252 is a CRITICAL (CVSS 9.9) deepstream is vulnerable to prototype vulnerability (CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')) affecting @deepstream/server libraries in the npm ecosystem. The issue involves deepstream is vulnerable to prototype pollution. Remediation is available by upgrading affected packages to version 10.0.5.

CVE-2026-49252 at a Glance

CVE Identifier CVE-2026-49252
GHSA Identifier GHSA-9v98-6g37-x9g6
Severity CRITICAL
CVSS v3.1 Base Score 9.9
CWE Classification CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
Affected Product @deepstream/server
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 9.9

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:L).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Changed (S:C)
Confidentiality High (C:H)
Integrity High (I:H)
Availability Low (A:L)

How to Fix CVE-2026-49252

To remediate this vulnerability, upgrade all affected @deepstream/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.

@deepstream/server fixed: 10.0.5 
npm install @deepstream/server@10.0.5
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 @deepstream/server

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-49252, inspect your project dependencies using npm:

npm ls @deepstream/server

Analyze the terminal output to locate any version of @deepstream/server in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 10.0.5), your application is affected.

Note: The npm ls @deepstream/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-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution'), where the product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype. In @deepstream/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 Prototype pollution in deepstream server v <=10.0.4. Potential privilege escalation from any authenticated user with write permission to any record. ### Patches Yes, upgrade to v10.0.5 ### Workarounds Filter out all messages containing the path `__proto__`, `constructor`, `prototype`, **before they reach the server's message pipeline**

CVE-2026-49252 Affected @deepstream/server Versions

1 component(s)
Fixed Versions:
10.0.5
Product / Package Ecosystem Affected Versions Fixed Version
@deepstream/server
npm/@deepstream/server
npm
< 10.0.5
10.0.5

References

GitHub Advisory / Wiki ADVISORY
https://github.com/deepstreamIO/deepstream.io/security/advisories/GHSA-9v98-6g37-x9g6
NVD — CVE-2026-49252 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-49252
Security Fix Commit FIX COMMIT
https://github.com/deepstreamIO/deepstream.io/commit/54b8e2958a98df444b5b5d9a66e22872afd84e44
@deepstream/server Source Repository REPOSITORY
https://github.com/deepstreamIO/deepstream.io

Frequently Asked Questions

What is CVE-2026-49252?
CVE-2026-49252 is a security vulnerability in @deepstream/server involving deepstream is vulnerable to prototype pollution under CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution').
Which @deepstream/server versions are affected?
Affected versions include releases prior to 10.0.5 across affected packages: @deepstream/server.
What version fixes CVE-2026-49252?
Upgrading to 10.0.5 (or the latest patched release for your respective branch) resolves the vulnerability.
Is @deepstream/server affected?
Yes, @deepstream/server is affected in releases prior to 10.0.5. Upgrade your dependency to 10.0.5 or later.
What is the CVSS score of CVE-2026-49252?
CVE-2026-49252 has a CVSS v3.1 base score of 9.9 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:L.
What CWE is associated with CVE-2026-49252?
CVE-2026-49252 is classified under CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') (The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype.).
How can I check npm dependencies for CVE-2026-49252?
Run the dependency tree command: 'npm ls @deepstream/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-9v98-6g37-x9g6",
  "modified" : "2026-06-26T21:03:59Z",
  "published" : "2026-06-26T21:03:59Z",
  "aliases" : [ "CVE-2026-49252" ],
  "summary" : "deepstream is vulnerable to prototype pollution",
  "details" : "### Impact\nPrototype pollution in deepstream server v <=10.0.4. Potential privilege escalation from any authenticated user with write permission to any record.\n\n### Patches\nYes, upgrade to v10.0.5\n\n### Workarounds\nFilter out all messages containing the path `__proto__`, `constructor`, `prototype`, **before they reach the server's message pipeline**",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@deepstream/server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "10.0.5"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/deepstreamIO/deepstream.io/security/advisories/GHSA-9v98-6g37-x9g6"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-49252"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/deepstreamIO/deepstream.io/commit/54b8e2958a98df444b5b5d9a66e22872afd84e44"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/deepstreamIO/deepstream.io"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1321" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-26T21:03:59Z",
    "nvd_published_at" : "2026-06-18T21:16:29Z"
  }
}