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CVE-2026-23830VulnerabilityPublished

CVE-2026-23830: nyariv SandboxJS · Code Injection

Affects nyariv SandboxJSSource CVE Database V5

0

Not known to be exploited · CVSS 10.0 Critical : upgrade to 0.8.26 as a priority.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 3.1 base score
10.0Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
1.2% chance of exploitation in 30 days – higher than 68% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 0.8.26
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 27 Jan 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-26.

What to do

Upgrade SandboxJS and nyariv/SandboxJS to 0.8.26.

Affected software

ProductAffectedFixed in
nyarivSandboxJSAffected
  • <0.8.26
Fixed in
  • 0.8.26
GitHubnyariv/SandboxJSpkg:github/nyariv/SandboxJSOther threatsAffected
  • <0.8.26
Fixed in
  • 0.8.26

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

European organizations should immediately audit their software supply chain and internal applications to identify any usage of SandboxJS versions prior to 0.8.26. The primary mitigation is to upgrade all instances of SandboxJS to version 0.8.26 or later, which patches the vulnerability by properly sandboxing AsyncFunction and related constructors. If upgrading is not immediately feasible, organizations should implement strict input validation and sandbox usage restrictions to limit exposure to untrusted code execution. Employ runtime monitoring and anomaly detection to identify suspicious behavior indicative of sandbox escape attempts. Additionally, isolate environments running sandboxed code with strict network segmentation and least privilege principles to contain potential breaches. Security teams should also review dependency management practices to ensure timely patching of third-party libraries. Finally, consider applying Web Application Firewalls (WAFs) and endpoint detection and response (EDR) solutions to detect and block exploitation attempts.

Description

SandboxJS is a JavaScript sandboxing library. Versions prior to 0.8.26 have a sandbox escape vulnerability due to `AsyncFunction` not being isolated in `SandboxFunction`. The library attempts to sandbox code execution by replacing the global `Function` constructor with a safe, sandboxed version (`SandboxFunction`). This is handled in `utils.ts` by mapping `Function` to `sandboxFunction` within a map used for lookups. However, before version 0.8.26, the library did not include mappings for `AsyncFunction`, `GeneratorFunction`, and `AsyncGeneratorFunction`. These constructors are not global properties but can be accessed via the `.constructor` property of an instance (e.g., `(async () => {}).constructor`). In `executor.ts`, property access is handled. When code running inside the sandbox accesses `.constructor` on an async function (which the sandbox allows creating), the `executor` retrieves the property value. Since `AsyncFunction` was not in the safe-replacement map, the `executor` returns the actual native host `AsyncFunction` constructor. Constructors for functions in JavaScript (like `Function`, `AsyncFunction`) create functions that execute in the global scope. By obtaining the host `AsyncFunction` constructor, an attacker can create a new async function that executes entirely outside the sandbox context, bypassing all restrictions and gaining full access to the host environment (Remote Code Execution). Version 0.8.26 patches this vulnerability.

References

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