Quick answers
- Is CVE-2026-25587 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-25587 being exploited in the wild.
- How severe is CVE-2026-25587?
- Low severity, with a CVSS score of 3.1, published 5 February 2026.
- Which products and versions are affected?
- @nyariv/sandboxjs (npm) SEMVER:introduced=0,fixed=0.8.29.
- Is there a fix for CVE-2026-25587?
- Yes. @nyariv/sandboxjs (npm): upgrade to 0.8.29 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-25587 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-25587?
- Check whether you run @nyariv/sandboxjs (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
How to fix
- @nyariv/sandboxjs (npm): upgrade to 0.8.29 or later
npm install @nyariv/sandboxjs@0.8.29
Technical details
The vulnerability is a sandbox escape caused by improper handling of prototypes in the sandbox implementation. Map is listed in SAFE_PROTOTYPES, but its prototype can be accessed and modified via Map.prototype. An attacker can overwrite Map.prototype.has with arbitrary code (e.g., isFinite), then use the Function constructor to execute arbitrary system commands. No authentication or user interaction is required; the vulnerability is triggered when the attacker-controlled payload is compiled and executed through the sandbox. The attack enables remote code execution on the underlying system. The vulnerability was patched in version 0.8.29; versions 0.8.28 and earlier are affected.
Affected products
- nyariv @nyariv/sandboxjs <=0.8.28
Identifiers
- CVE-2026-25587
- GHSA-66h4-qj4x-38xp
Timeline
- 2026-02-05: disclosed
- 2026-02-05: patched: Version 0.8.29 released with fix