CVE-2026-39321: Parse server Parse Server Has A Login Vulnerability

MODERATE
Advisory Identifier: GHSA-mmpq-5hcv-hf2v
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CVSS 3.7
CWE-208
Published
Advisory Summary

CVE-2026-39321 is a MODERATE (CVSS 3.7) parse server has a login vulnerability (CWE-208: Observable Timing Discrepancy) affecting Parse server libraries in the npm ecosystem. The issue involves parse server has a login timing side-channel reveals user existence. Remediation is available by upgrading affected packages to version 9.8.0-alpha.6, 8.6.74.

CVE-2026-39321 at a Glance

CVE Identifier CVE-2026-39321
GHSA Identifier GHSA-mmpq-5hcv-hf2v
Severity MODERATE
CVSS v3.1 Base Score 3.7
CWE Classification CWE-208: Observable Timing Discrepancy
Affected Product Parse server
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 3.7

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

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

How to Fix CVE-2026-39321

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: 9.8.0-alpha.6 
npm install parse-server@9.8.0-alpha.6
parse-server fixed: 8.6.74 
npm install parse-server@8.6.74
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-2026-39321, 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 9.8.0-alpha.6), 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-208: Observable Timing Discrepancy, where two separate operations in a product require different amounts of time to complete, in a way that is observable to an actor and reveals security-relevant information about the state of the product, such as whether a particular operation was successful or not. 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 The login endpoint response time differs measurably depending on whether the submitted username or email exists in the database. When a user is not found, the server responds immediately. When a user exists but the password is wrong, a bcrypt comparison runs first, adding significant latency. This timing difference allows an unauthenticated attacker to enumerate valid usernames. ### Patches A dummy bcrypt comparison is now performed when no user is found, normalizing response timing regardless of user existence. Additionally, accounts without a stored password (e.g. OAuth-only) now also run a dummy comparison to prevent the same timing oracle. ### Workarounds Configure rate limiting on the login endpoint to slow automated enumeration. This reduces throughput but does not eliminate the timing signal for individual requests.

CVE-2026-39321 Affected Parse server Versions

2 component(s)
Fixed Versions:
9.8.0-alpha.68.6.74
Product / Package Ecosystem Affected Versions Fixed Version
parse-server
npm/parse-server
npm
≥ 9.0.0
< 9.8.0-alpha.6
9.8.0-alpha.6
parse-server
npm/parse-server
npm
< 8.6.74
8.6.74

References

GitHub Advisory / Wiki ADVISORY
https://github.com/parse-community/parse-server/security/advisories/GHSA-mmpq-5hcv-hf2v
NVD — CVE-2026-39321 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-39321
Parse server Source Repository REPOSITORY
https://github.com/parse-community/parse-server/pull/10398
Parse server Source Repository REPOSITORY
https://github.com/parse-community/parse-server/pull/10399
Parse server Source Repository REPOSITORY
https://github.com/parse-community/parse-server

Frequently Asked Questions

What is CVE-2026-39321?
CVE-2026-39321 is a security vulnerability in Parse server involving Parse Server has a login timing side-channel reveals user existence under CWE-208: Observable Timing Discrepancy.
Which Parse server versions are affected?
Affected versions include releases prior to 9.8.0-alpha.6, 8.6.74 across affected packages: parse-server.
What version fixes CVE-2026-39321?
Upgrading to 9.8.0-alpha.6, 8.6.74 (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 9.8.0-alpha.6, 8.6.74. Upgrade your dependency to 9.8.0-alpha.6, 8.6.74 or later.
What is the CVSS score of CVE-2026-39321?
CVE-2026-39321 has a CVSS v3.1 base score of 3.7 (MODERATE) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N.
What CWE is associated with CVE-2026-39321?
CVE-2026-39321 is classified under CWE-208: Observable Timing Discrepancy (Two separate operations in a product require different amounts of time to complete, in a way that is observable to an actor and reveals security-relevant information about the state of the product, such as whether a particular operation was successful or not.).
How can I check npm dependencies for CVE-2026-39321?
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-mmpq-5hcv-hf2v",
  "modified" : "2026-04-15T21:17:16Z",
  "published" : "2026-04-08T00:07:10Z",
  "aliases" : [ "CVE-2026-39321" ],
  "summary" : "Parse Server has a login timing side-channel reveals user existence",
  "details" : "### Impact\n\nThe login endpoint response time differs measurably depending on whether the submitted username or email exists in the database. When a user is not found, the server responds immediately. When a user exists but the password is wrong, a bcrypt comparison runs first, adding significant latency. This timing difference allows an unauthenticated attacker to enumerate valid usernames.\n\n### Patches\n\nA dummy bcrypt comparison is now performed when no user is found, normalizing response timing regardless of user existence. Additionally, accounts without a stored password (e.g. OAuth-only) now also run a dummy comparison to prevent the same timing oracle.\n\n### Workarounds\n\nConfigure rate limiting on the login endpoint to slow automated enumeration. This reduces throughput but does not eliminate the timing signal for individual requests.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "parse-server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "9.0.0"
      }, {
        "fixed" : "9.8.0-alpha.6"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "parse-server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "8.6.74"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/parse-community/parse-server/security/advisories/GHSA-mmpq-5hcv-hf2v"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-39321"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/parse-community/parse-server/pull/10398"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/parse-community/parse-server/pull/10399"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/parse-community/parse-server"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-208" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-04-08T00:07:10Z",
    "nvd_published_at" : "2026-04-07T18:16:43Z"
  }
}