Unauthenticated RCE via Deserialization in Replicator npm

Compliance Impact

The provided context and resources do not explicitly discuss the impact of CVE-2026-2265 on compliance with common standards and regulations such as GDPR or HIPAA.

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Executive Summary

CVE-2026-2265 is a critical remote code execution (RCE) vulnerability in the Replicator npm package version 1.0.5 and earlier. It arises from unsafe deserialization of untrusted user input, specifically during the reconstruction of Error objects. The vulnerability allows an attacker to control the "name" field in serialized input, which is used to select a constructor from the global scope without restriction. This enables the attacker to specify dangerous constructors like "Function" to execute arbitrary code on the victim's machine.

A proof of concept demonstrates this by crafting a JSON string that, when deserialized by replicator.decode(), executes a command such as opening the Calculator application. The root cause is the unsafe dynamic constructor resolution during deserialization, which was fixed by implementing a strict allowlist of safe error constructors to prevent arbitrary code execution.

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Impact Analysis

This vulnerability can lead to remote code execution on systems using the vulnerable Replicator package. An attacker can send specially crafted serialized data that, when deserialized, executes arbitrary commands on the target system without authentication.

Such an exploit can compromise the confidentiality, integrity, and availability of affected systems by allowing attackers to run malicious code, potentially leading to data theft, system takeover, or disruption of services.

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Detection Guidance

This vulnerability can be detected by identifying usage of the Replicator npm package version 1.0.5 or earlier in your applications, especially where untrusted user input is deserialized using replicator.decode().

A practical detection method involves monitoring or scanning for suspicious deserialization calls that use the replicator.decode() function with crafted JSON input containing Error objects with unusual "name" fields that could lead to code execution.

While no specific detection commands are provided in the resources, you can search your codebase for the usage of replicator.decode() and check the version of the replicator package installed.

• Check replicator package version in your project: `npm list replicator`
• Search code for usage of replicator.decode(): `grep -r "replicator.decode" ./`
• Monitor logs or network traffic for JSON payloads containing suspicious Error objects with unusual "name" fields that could trigger unsafe deserialization.

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Mitigation Strategies

Immediate mitigation steps include upgrading the Replicator package to a version that includes the security patch from PR #19, which implements a strict allowlist of safe error constructors to prevent unsafe deserialization.

Additional recommended actions are to avoid deserializing untrusted input with replicator.decode(), validate and sanitize all input before deserialization, and treat all deserialized objects as untrusted until properly validated.

• Upgrade replicator package to a patched version that includes the fix from PR #19.
• Implement strict allowlists for error constructors during deserialization to prevent arbitrary code execution.
• Audit your codebase for unsafe usage of replicator.decode() and avoid deserializing data from untrusted sources.
• Add security tests to detect unexpected constructor names or malicious payloads.

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