Scope modification via unsanitized New handler objects
Published Apr 6, 2026 · Updated Apr 6, 2026
Scope modification in SandboxJS before 0.8.36 allows attackers to alter higher-level scope variables through crafted sandboxed code. The New operator handler in src/executor.ts passes raw Prop wrappers to constructors and returns constructed objects without sanitizing either path. The host must execute attacker-controlled code and read the sandbox result; code evaluation remains sandboxed, and protected prototypes stay unchanged.
Summary
What happened
Scope modification in SandboxJS before 0.8.36 allows attackers to alter higher-level scope variables through crafted sandboxed code. The New operator handler in src/executor.ts passes raw Prop wrappers to constructors and returns constructed objects without sanitizing either path. The host must execute attacker-controlled code and read the sandbox result; code evaluation remains sandboxed, and protected prototypes stay unchanged.
The record
- CVE
- CVE-2026-34217
- Published
- Apr 6, 2026
- Updated
- Apr 6, 2026
- Vendor
- nyariv
- Product
- SandboxJS
- Classifications
- CWE-668
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Apr 6, 2026CVE publishedPublication date reported by the CVE source.
- Apr 6, 2026Record 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=< 0.8.36
What conditions does exploitation require?
What is affected?
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
- New handler Prop-object leak proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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