Host code execution via unwrapped function returns
Published Feb 6, 2026 · Updated Feb 6, 2026
Sandbox escape in nyariv SandboxJS before 0.8.29 allows attackers to execute arbitrary host JavaScript through sandboxed code. Object.values or Object.entries returns an unwrapped host array, and Array.prototype.at exposes the host Function constructor from that array. Reachability requires a consuming application to evaluate attacker-controlled JavaScript; successful exploitation escapes the library's restrictions and executes with the host process's authority.
Summary
What happened
Sandbox escape in nyariv SandboxJS before 0.8.29 allows attackers to execute arbitrary host JavaScript through sandboxed code. Object.values or Object.entries returns an unwrapped host array, and Array.prototype.at exposes the host Function constructor from that array. Reachability requires a consuming application to evaluate attacker-controlled JavaScript; successful exploitation escapes the library's restrictions and executes with the host process's authority.
The record
- CVE
- CVE-2026-25520
- Published
- Feb 6, 2026
- Updated
- Feb 6, 2026
- Vendor
- nyariv
- Product
- SandboxJS
- Classifications
- CWE-74, T1059.007
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Feb 6, 2026CVE publishedPublication date reported by the CVE source.
- Feb 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=< 0.8.29
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
- GHSA-58jh-xv4v-pcx4 proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
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