Object prototype pollution via unchecked URL key paths
Published Apr 23, 2021 · Updated Aug 3, 2024
Prototype pollution in Purl 2.3.2 allows attackers to modify Object.prototype via crafted URL query or fragment parameters. The parseString, merge, and recursive parse functions process decoded key paths without rejecting proto or constructor[prototype], allowing assignments to traverse inherited objects. Exploitation requires an application to parse attacker-controlled URL data; downstream consequences depend on code that consumes polluted inherited properties.
Summary
What happened
Prototype pollution in Purl 2.3.2 allows attackers to modify Object.prototype via crafted URL query or fragment parameters. The parseString, merge, and recursive parse functions process decoded key paths without rejecting proto or constructor[prototype], allowing assignments to traverse inherited objects. Exploitation requires an application to parse attacker-controlled URL data; downstream consequences depend on code that consumes polluted inherited properties.
The record
- CVE
- CVE-2021-20089
- Published
- Apr 23, 2021
- Updated
- Aug 3, 2024
- Vendor
- Purl Project
- Product
- Purl
- Classifications
- CWE-1321
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Apr 23, 2021CVE publishedPublication date reported by the CVE source.
- Aug 3, 2024Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=2.3.2
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- BlackFan Purl prototype-pollution proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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