# CVE-2026-39321: Parse Server has a login timing side-channel reveals user existence

> An unauthenticated attacker can enumerate valid usernames by measuring response time differences in the login endpoint.

- **Severity:** Medium 6.3 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 7 Apr 2026
- **Updated:** 7 Apr 2026
- **Also known as:** BIT-parse-2026-39321, GHSA-mmpq-5hcv-hf2v

## What is CVE-2026-39321?

CVE-2026-39321 is a medium-severity vulnerability in Parseplatform Parse-Server, published on 7 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to 9.8.0-alpha.6 and 8.6.74, he 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. This vulnerability is fixed in 9.8.0-alpha.6 and 8.6.74.

Weakness: CWE-208 (Observable Timing Discrepancy)

## Which versions are affected by CVE-2026-39321?

5 open source packages ship an affected version, including parse-server and parse. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `parse-server` | npm | All versions | 8.6.74 |
| `parse-server` | npm | All versions | 8.6.74 |
| `parse-server` | npm | From 9.0.0 | 9.8.0-alpha.6 |
| `parse-server` | npm | From 9.0.0 | 9.8.0-alpha.6 |
| `parse` | Bitnami | All versions | 8.6.74, 9.8.0 |

Products: Parseplatform Parse-Server.

## How do I fix CVE-2026-39321?

Upgrade parse-server to a fixed version for your release line: 8.6.74 or 9.8.0-alpha.6.

## Is CVE-2026-39321 being exploited?

There is no known exploitation of CVE-2026-39321 in the wild and no public exploit code.

## Other vulnerabilities in Parseplatform Parse-Server

- [CVE-2026-30966](https://insights.sbomify.com/CVE-2026-30966/): Parse Server role escalation and CLP bypass via direct `_Join` table write (critical 10.0)
- [CVE-2024-27298](https://insights.sbomify.com/CVE-2024-27298/): Parse Server literalizeRegexPart SQL Injection (critical 10.0)
- [CVE-2022-24760](https://insights.sbomify.com/CVE-2022-24760/): Command Injection in Parse server (critical 10.0)
- [CVE-2026-30965](https://insights.sbomify.com/CVE-2026-30965/): Parse Server session token exfiltration via `redirectClassNameForKey` query parameter (critical 9.9)
- [CVE-2023-36475](https://insights.sbomify.com/CVE-2023-36475/): Parse Server vulnerable to remote code execution via MongoDB BSON parser through prototype pollution (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-39321 and fix it if it is affected.

What it is: CVE-2026-39321 is a medium-severity vulnerability in Parseplatform Parse-Server, published on 7 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-39321 in the wild and no public exploit code.

Affected packages and fixed versions:
- parse-server (npm): affected all versions; fixed in 8.6.74
- parse-server (npm): affected all versions; fixed in 8.6.74
- parse-server (npm): affected from 9.0.0; fixed in 9.8.0-alpha.6
- parse-server (npm): affected from 9.0.0; fixed in 9.8.0-alpha.6
- parse (Bitnami): affected all versions; fixed in 8.6.74, 9.8.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-39321/ (Markdown: https://insights.sbomify.com/CVE-2026-39321/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-39321
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-39321
- OSV: https://osv.dev/vulnerability/CVE-2026-39321

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-39321/
Summaries are generated and may contain mistakes; the official description above is the record.