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fast-xml-parser vulnerable to Prototype Pollution through tag or attribute name

Moderate severity GitHub Reviewed Published Jun 11, 2023 in NaturalIntelligence/fast-xml-parser • Updated Dec 14, 2023

Package

npm fast-xml-parser (npm)

Affected versions

< 4.1.2

Patched versions

4.1.2

Description

Impact

As a part of this vulnerability, user was able to se code using __proto__ as a tag or attribute name.

const { XMLParser, XMLBuilder, XMLValidator} = require("fast-xml-parser");

let XMLdata = "<__proto__><polluted>hacked</polluted></__proto__>"

const parser = new XMLParser();
let jObj = parser.parse(XMLdata);

console.log(jObj.polluted) // should return hacked

Patches

The problem has been patched in v4.1.2

Workarounds

User can check for "proto" in the XML string before parsing it to the parser.

References

https://gist.github.com/Sudistark/a5a45bd0804d522a1392cb5023aa7ef7

References

@amitguptagwl amitguptagwl published to NaturalIntelligence/fast-xml-parser Jun 11, 2023
Published to the GitHub Advisory Database Jun 13, 2023
Reviewed Jun 13, 2023
Published by the National Vulnerability Database Dec 12, 2023
Last updated Dec 14, 2023

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

EPSS score

0.073%
(33rd percentile)

Weaknesses

CVE ID

CVE-2023-26920

GHSA ID

GHSA-x3cc-x39p-42qx

Source code

Credits

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