Prototype pollution via unsafe deepFromFlat path traversal
Published Jun 28, 2022 · Updated Apr 22, 2025
Prototype pollution in Clever underscore.deep before 0.5.3 allows attackers to modify future objects through crafted flattened keys. deepFromFlat walks dot-separated key paths and assigns into t[part] without rejecting proto, constructor, or prototype segments. Applications are exposed only when attacker-controlled data reaches deepFromFlat directly or through deepPick; inherited properties can then alter application behavior.
Summary
What happened
Prototype pollution in Clever underscore.deep before 0.5.3 allows attackers to modify future objects through crafted flattened keys. deepFromFlat walks dot-separated key paths and assigns into t[part] without rejecting proto, constructor, or prototype segments. Applications are exposed only when attacker-controlled data reaches deepFromFlat directly or through deepPick; inherited properties can then alter application behavior.
The record
- CVE
- CVE-2022-31106
- Published
- Jun 28, 2022
- Updated
- Apr 22, 2025
- Vendor
- Clever
- Product
- underscore.deep
- Classifications
- CWE-1321
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 28, 2022CVE publishedPublication date reported by the CVE source.
- Apr 22, 2025Record 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=< 0.5.3
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
- Upstream deepFromFlat prototype-pollution regression payloadproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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