CVE-2021-39187 Crash server with query parameter
An attacker can crash the Parse Server by sending a query with an invalid explain option, causing a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2021-39187?
CVE-2021-39187 is a high-severity denial of service vulnerability in Parseplatform Parse-Server, published on 2 Sep 2021. 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 version 4.10.3, Parse Server crashes when if a query request contains an invalid value for the `explain` option. This is due to a bug in the MongoDB Node.js driver which throws an exception that Parse Server cannot catch. There is a patch for this issue in version 4.10.3. No workarounds aside from upgrading are known to exist.
Which versions are affected by CVE-2021-39187?
3 open source packages ship an affected version, including parse-server and parse. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
parse-server npm | All versions | 4.10.3 |
parse-server npm | All versions | 4.10.3 |
parse Bitnami | All versions | 4.10.3 |
Products include Parseplatform Parse-Server.
How do I fix CVE-2021-39187?
Upgrade parse-server to 4.10.3 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2021-39187 being exploited?
There is no known exploitation of CVE-2021-39187 in the wild and no public exploit code.
Other vulnerabilities in Parseplatform Parse-Server
- CVE-2026-30966 Parse Server role escalation and CLP bypass via direct `_Join` table write
- CVE-2024-27298 Parse Server literalizeRegexPart SQL Injection
- CVE-2022-24760 Command Injection in Parse server
- CVE-2026-30965 Parse Server session token exfiltration via `redirectClassNameForKey` query parameter
- CVE-2023-36475 Parse Server vulnerable to remote code execution via MongoDB BSON parser through prototype pollution
Sources
Also known as BIT-parse-2021-39187, GHSA-xqp8-w826-hh6x.