CVE-2026-33624: Parse Server MFA Recovery Code Single-use Bypass Vulnerability

LOW
Advisory Identifier: GHSA-2299-ghjr-6vjp
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CWE-367
Published
Advisory Summary

CVE-2026-33624 is a LOW mfa recovery code single-use bypass vulnerability (CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition) affecting Parse Server libraries in the npm ecosystem. The issue involves mfa recovery code single-use bypass via concurrent requests. Remediation is available by upgrading affected packages to version 9.6.0-alpha.54, 8.6.60.

CVE-2026-33624 at a Glance

CVE Identifier CVE-2026-33624
GHSA Identifier GHSA-2299-ghjr-6vjp
Severity LOW
CVSS v3.1 Base Score N/A
CWE Classification CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition
Affected Product Parse Server
Package Ecosystem npm
Published Date
Last Updated

How to Fix CVE-2026-33624

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.54 
npm install parse-server@9.6.0-alpha.54
parse-server fixed: 8.6.60 
npm install parse-server@8.6.60
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-2026-33624, 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.54), 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-367: Time-of-check Time-of-use (TOCTOU) Race Condition, where the product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check. 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 who obtains a user's password and a single MFA recovery code can reuse that recovery code an unlimited number of times by sending concurrent login requests. This defeats the single-use design of recovery codes. The attack requires the user's password, a valid recovery code, and the ability to send concurrent requests within milliseconds. ### Patches The login handler now uses optimistic locking when updating auth data that contains consumed single-use tokens. If a concurrent request has already modified the recovery array, the update fails and the login is rejected. ### Workarounds There are no known workarounds.

CVE-2026-33624 Affected Parse Server Versions

2 component(s)
Fixed Versions:
9.6.0-alpha.548.6.60
Product / Package Ecosystem Affected Versions Fixed Version
parse-server
npm/parse-server
npm
≥ 9.0.0
< 9.6.0-alpha.54
9.6.0-alpha.54
parse-server
npm/parse-server
npm
< 8.6.60
8.6.60

References

GitHub Advisory / Wiki ADVISORY
https://github.com/parse-community/parse-server/security/advisories/GHSA-2299-ghjr-6vjp
NVD — CVE-2026-33624 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-33624
Parse Server Source Repository REPOSITORY
https://github.com/parse-community/parse-server/pull/10275
Parse Server Source Repository REPOSITORY
https://github.com/parse-community/parse-server/pull/10276
Security Fix Commit FIX COMMIT
https://github.com/parse-community/parse-server/commit/5e70094250a36bfcc14ecd49592be2b94fba66ff
Security Fix Commit FIX COMMIT
https://github.com/parse-community/parse-server/commit/fc3da35a81d5083b453e8967cabcc880f1a3bd0c
Parse Server Source Repository REPOSITORY
https://github.com/parse-community/parse-server

Frequently Asked Questions

What is CVE-2026-33624?
CVE-2026-33624 is a security vulnerability in Parse Server involving MFA recovery code single-use bypass via concurrent requests under CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition.
Which Parse Server versions are affected?
Affected versions include releases prior to 9.6.0-alpha.54, 8.6.60 across affected packages: parse-server.
What version fixes CVE-2026-33624?
Upgrading to 9.6.0-alpha.54, 8.6.60 (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.54, 8.6.60. Upgrade your dependency to 9.6.0-alpha.54, 8.6.60 or later.
What CWE is associated with CVE-2026-33624?
CVE-2026-33624 is classified under CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition (The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.).
How can I check npm dependencies for CVE-2026-33624?
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-2299-ghjr-6vjp",
  "modified" : "2026-03-27T21:54:30Z",
  "published" : "2026-03-24T19:48:24Z",
  "aliases" : [ "CVE-2026-33624" ],
  "summary" : "Parse Server: MFA recovery code single-use bypass via concurrent requests",
  "details" : "### Impact\n\nAn attacker who obtains a user's password and a single MFA recovery code can reuse that recovery code an unlimited number of times by sending concurrent login requests. This defeats the single-use design of recovery codes. The attack requires the user's password, a valid recovery code, and the ability to send concurrent requests within milliseconds.\n\n### Patches\n\nThe login handler now uses optimistic locking when updating auth data that contains consumed single-use tokens. If a concurrent request has already modified the recovery array, the update fails and the login is rejected.\n\n### Workarounds\n\nThere are no known workarounds.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
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    },
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  } ],
  "references" : [ {
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  }, {
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    "type" : "PACKAGE",
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  } ],
  "database_specific" : {
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    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-24T19:48:24Z",
    "nvd_published_at" : "2026-03-24T19:16:55Z"
  }
}