# CVE-2020-5251: Information disclosure in parse-server

> Attackers can extract valid session tokens via regex queries to take over user accounts in Parse Server.

- **Severity:** High 7.7 (`CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 4 Mar 2020
- **Updated:** 4 Aug 2024
- **Also known as:** BIT-parse-2020-5251, GHSA-h4mf-75hf-67w4

## What is CVE-2020-5251?

CVE-2020-5251 is a high-severity vulnerability in Parseplatform Parse-Server, published on 4 Mar 2020. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

In parser-server before version 4.1.0, you can fetch all the users objects, by using regex in the NoSQL query. Using the NoSQL, you can use a regex on sessionToken and find valid accounts this way.

Weakness: CWE-863 (Incorrect Authorization), CWE-285 (Improper Authorization)

## Which versions are affected by CVE-2020-5251?

3 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 | 4.1.0 |
| `parse-server` | npm | All versions | 4.1.0 |
| `parse` | Bitnami | All versions | 4.1.0 |

Products: Parseplatform Parse-Server.

## How do I fix CVE-2020-5251?

Upgrade parse-server to 4.1.0 or later.

## Is CVE-2020-5251 being exploited?

There is no known exploitation of CVE-2020-5251 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-2020-5251 and fix it if it is affected.

What it is: CVE-2020-5251 is a high-severity vulnerability in Parseplatform Parse-Server, published on 4 Mar 2020. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2020-5251 in the wild and no public exploit code.

Affected packages and fixed versions:
- parse-server (npm): affected all versions; fixed in 4.1.0
- parse-server (npm): affected all versions; fixed in 4.1.0
- parse (Bitnami): affected all versions; fixed in 4.1.0

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-2020-5251/ (Markdown: https://insights.sbomify.com/CVE-2020-5251/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-5251
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-5251
- OSV: https://osv.dev/vulnerability/CVE-2020-5251

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-5251/
Summaries are generated and may contain mistakes; the official description above is the record.