CVE-2020-28279
flattenizer vulnerable to prototype pollution
Prototype pollution vulnerability in 'flattenizer' versions 0.0.5 through 1.0.5 allows an attacker to cause a denial of service and may lead to remote code execution.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
NVD Score used
9.8
Prototype pollution vulnerability in 'flattenizer' versions 0.0.5 through 1.0.5 allows an attacker to cause a denial of service and may lead to remote code execution.
- Record
CVE-2020-28279- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - CVSS 2.0
- 7.5 High
AV:N/AC:L/Au:N/C:P/I:P/A:P - Updated
- 2026-11-02
CVE List No score
Prototype pollution vulnerability in 'flattenizer' versions 0.0.5 through 1.0.5 allows an attacker to cause a denial of service and may lead to remote code execution.
- Record
CVE-2020-28279- Updated
- 2026-11-02
EUVDEUVD-2022-5400 No score
Prototype pollution vulnerability in 'flattenizer' versions 0.0.5 through 1.0.5 allows an attacker to cause a denial of service and may lead to remote code execution.
- Record
EUVD-2022-5400- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-vq33-26pr-r4h6
9.8
flattenizer vulnerable to prototype pollution
Overview
Prototype pollution vulnerability in ‘flattenizer’ versions 0.0.5 through 1.0.5 allows an attacker to cause a denial of service and may lead to remote code execution.
Details
The NPM module 'flattenizer' can be abused by Prototype Pollution vulnerability since the function 'unflatten()' did not check for the type of object before assigning value to the property. Due to this flaw an attacker could create a non-existent property or able to manipulate the property which leads to Denial of Service or potentially Remote code execution.
PoC Details
There is no validation before assigning the property to check whether the assigned argument is the Object's own property or not, the property polluted will be directly be assigned thereby polluting the Object prototype. Later in the code, if there is a check to validate polluted the valued would be substituted as "true" as it had been polluted.
var flattenizer = require("flattenizer")
flattenizer.unflatten({'__proto__.polluted': true});
console.log(polluted);
- Record
GHSA-vq33-26pr-r4h6- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-1321
- Updated
- 2026-11-02
OSVGHSA-vq33-26pr-r4h6
9.8
flattenizer vulnerable to prototype pollution
Overview
Prototype pollution vulnerability in ‘flattenizer’ versions 0.0.5 through 1.0.5 allows an attacker to cause a denial of service and may lead to remote code execution.
Details
The NPM module 'flattenizer' can be abused by Prototype Pollution vulnerability since the function 'unflatten()' did not check for the type of object before assigning value to the property. Due to this flaw an attacker could create a non-existent property or able to manipulate the property which leads to Denial of Service or potentially Remote code execution.
PoC Details
There is no validation before assigning the property to check whether the assigned argument is the Object's own property or not, the property polluted will be directly be assigned thereby polluting the Object prototype. Later in the code, if there is a check to validate polluted the valued would be substituted as "true" as it had been polluted.
var flattenizer = require("flattenizer")
flattenizer.unflatten({'__proto__.polluted': true});
console.log(polluted);
- Record
GHSA-vq33-26pr-r4h6- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-1321
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
flattenizernpm |
0.0.5 to 1.0.5 | 1.1.1 |
flattenizernpm |
0.0.5 up to 1.1.1 | 1.1.1 |
History
| Recorded | Changed | Sources |
|---|---|---|
| facts | ||
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2020-28279 is a critical vulnerability (CVSS 9.8) in Flattenizer Project Flattenizer, published December 29, 2020. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 3.11%, the 87th percentile. Fixed in flattenizer 1.1.1.
References
github.com/sahellebusch/flattenizer/pull/13
whitesourcesoftware.com/vulnerability-database/CVE-2020-28279
nvd.nist.gov/vuln/detail/CVE-2020-28279
github.com/sahellebusch/flattenizer/commit/3c6a6353df7c8879e931973b81a49a47f6c2b399
web.archive.org/web/20210104205035/https://www.whitesourcesoftware.com/vulnerability-database/CVE-2020-28279
github.com/advisories/GHSA-vq33-26pr-r4h6