CVE-2026-23830

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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."}, {"lang": "es", "value": "SandboxJS es una librer\u00eda de sandboxing de JavaScript. Las versiones anteriores a la 0.8.26 tienen una vulnerabilidad de escape de sandbox debido a que `AsyncFunction` no est\u00e1 aislada en `SandboxFunction`. La librer\u00eda intenta aplicar un sandbox a la ejecuci\u00f3n de c\u00f3digo reemplazando el constructor global `Function` con una versi\u00f3n segura y con sandbox (`SandboxFunction`). Esto se maneja en `utils.ts` mapeando `Function` a `sandboxFunction` dentro de un mapa utilizado para b\u00fasquedas. Sin embargo, antes de la versi\u00f3n 0.8.26, la librer\u00eda no inclu\u00eda mapeos para `AsyncFunction`, `GeneratorFunction` y `AsyncGeneratorFunction`. Estos constructores no son propiedades globales, pero se puede acceder a ellos a trav\u00e9s de la propiedad `.constructor` de una instancia (por ejemplo, `(async () =&gt; {}).constructor`). En `executor.ts`, se maneja el acceso a propiedades. Cuando el c\u00f3digo que se ejecuta dentro del sandbox accede a `.constructor` en una funci\u00f3n as\u00edncrona (que el sandbox permite crear), el `executor` recupera el valor de la propiedad. Dado que `AsyncFunction` no estaba en el mapa de reemplazo seguro, el `executor` devuelve el constructor `AsyncFunction` nativo real del host. Los constructores para funciones en JavaScript (como `Function`, `AsyncFunction`) crean funciones que se ejecutan en el \u00e1mbito global. Al obtener el constructor `AsyncFunction` del host, un atacante puede crear una nueva funci\u00f3n as\u00edncrona que se ejecuta completamente fuera del contexto del sandbox, eludiendo todas las restricciones y obteniendo acceso total al entorno del host (ejecuci\u00f3n remota de c\u00f3digo). La versi\u00f3n 0.8.26 corrige esta vulnerabilidad."}], "id": "CVE-2026-23830", "lastModified": "2026-06-17T10:22:10.250", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 10.0, "baseSeverity": "CRITICAL", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "CHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 6.0, "source": "security-advisories@github.com", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-23830", "options": [{"exploitation": "poc"}, {"automatable": "yes"}, {"technicalImpact": "total"}], "role": "CISA Coordinator", "timestamp": "2026-01-28T15:09:12.332920Z", "version": "2.0.3"}}]}, "published": "2026-01-28T00:15:50.170", "references": [{"source": "security-advisories@github.com", "tags": ["Patch"], "url": "https://github.com/nyariv/SandboxJS/commit/345aee6566e47979dee5c337b925b141e7f78ccd"}, {"source": "security-advisories@github.com", "tags": ["Exploit", "Vendor Advisory"], "url": "https://github.com/nyariv/SandboxJS/security/advisories/GHSA-wxhw-j4hc-fmq6"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-94"}, {"lang": "en", "value": "CWE-693"}, {"lang": "en", "value": "CWE-913"}], "source": "security-advisories@github.com", "type": "Secondary"}]}

{}

{"analysis": {"en": {"generated_at": "2026-04-18T01:52:40.774956+00:00", "value": {"mitigation_remediation": ["Upgrade SandboxJS to version\u00a00.8.26 or newer.", "If an upgrade is not immediately feasible, modify the sandbox\u2019s utilities to map the AsyncFunction constructor to the safe replacement, ensuring that .constructor lookups invoke the sandboxed implementation.", "Audit any application code that relies on sandboxed execution to confirm that no untrusted input can trigger the vulnerable async function construction path."], "summary": {"action": "Immediate Patch", "impact": "Remote Code Execution"}, "threat_synthesis": {"affected_systems": "Users of the JavaScript sandboxing library from the developer known as nyariv, specifically any installations of SandboxJS with a version older than 0.8.26, are affected. The vulnerability exists in the library\u2019s implementation of sandboxed function construction and persists until the update is applied.", "description_and_impact": "The vulnerability in versions of the sandboxing library prior to 0.8.26 stems from the fact that the global constructor for asynchronous functions is not replaced during the sandboxing process. This oversight allows code that runs inside the sandbox to retrieve the native AsyncFunction constructor through the .constructor property of an async function instance. Constructing a new async function with this native constructor executes code in the host environment rather than within the isolated sandbox, enabling attackers to run arbitrary code with all privileges of the host process. The flaw is characterized by the weaknesses listed in CWE\u2011693, CWE\u2011913, and CWE\u201194.", "risk_and_exploitability": "Given the CVSS score of 10, the potential impact of this flaw is maximum; an attacker can completely escape the sandbox and execute arbitrary code. The EPSS score of less than 1 percent indicates that, while the likelihood of exploitation is currently low, the severity dictates that it should be treated with urgency. The vulnerability has not yet been listed in the CISA Known Exploited Vulnerabilities catalog, but the lack of a catalog entry does not diminish the need for timely remediation. Without a patch, the flaw can be exploited by any code path that creates or accesses asynchronous functions within the sandbox."}}}}, "created": "2026-01-28T12:22:20.235396+00:00", "updated": "2026-04-18T02:00:10.465887+00:00", "vendors": ["nyariv", "nyariv$PRODUCT$sandboxjs"]}