CVE-2026-23830: nyariv SandboxJS · Code Injection
Affects nyariv SandboxJSSource CVE Database V5
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
- 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:HExploitation evidence
Disclosed: evidence found.
CVE published 27 Jan 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
| Product | Affected | Fixed in |
|---|---|---|
| nyarivSandboxJS | Affected
| Fixed in
|
GitHubnyariv/SandboxJSpkg:github/nyariv/SandboxJSOther threats | Affected
| Fixed in
|
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.