Remote code execution via unsafe recursive merge
Published Aug 11, 2023 · Updated Oct 9, 2024
Prototype pollution in MrSwitch hello.js 1.18.6 allows remote attackers to execute arbitrary code through hello.utils.extend. The recursive merge enumerates attacker-controlled keys and assigns them without blocking proto, allowing inherited properties to alter Object.prototype. The upstream proof of concept supplies crafted state through the URL fragment and demonstrates script execution in a consuming web page.
Summary
What happened
Prototype pollution in MrSwitch hello.js 1.18.6 allows remote attackers to execute arbitrary code through hello.utils.extend. The recursive merge enumerates attacker-controlled keys and assigns them without blocking proto, allowing inherited properties to alter Object.prototype. The upstream proof of concept supplies crafted state through the URL fragment and demonstrates script execution in a consuming web page.
The record
- CVE
- CVE-2021-26505
- Published
- Aug 11, 2023
- Updated
- Oct 9, 2024
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-1321, T1203
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 11, 2023CVE publishedPublication date reported by the CVE source.
- Oct 9, 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?
What conditions does exploitation require?
What is affected?
Affected products and versions are unavailable in this record.
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
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
- hello.js URL-fragment 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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