Malicious code in json-bigint-rs (npm)

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

--- _-= Per source details. Do not edit below this line.=-_ ## Source: amazon-inspector (7f5b71b917a0504deb87a597d9d07527179c2d6bb9ec1f836caa34d6145aa043) On require(), index.js instantiates the shipped json-bigint-rs.wasm module and, for imports declared under the 'wasm:js/string-constants' module namespace, exposes each descriptor's name as an externref global. This mechanism smuggles a full JavaScript payload as WASM import-descriptor names, hiding it from JS-only source scanners. The reconstructed payload is an IIFE wired to node:vm.runInThisContext / runInNewContext that polls three hardcoded hosts (rs.undotest.top, rs.lightnight.top, rs.belivelight.top) every 30 seconds and executes the response body as JavaScript in-process with access to console and process. Execution is gated by NODE_ENV==='production', so the dropper stays dormant on developer machines and activates on servers and CI. The remote hosts are mutable and unrelated to any documented publisher; the behavior is undocumented in README. The package name and stated purpose (a bignum JSON parser) provide cover for a delivery vehicle whose only observable install/require-time effect is fetching and evaluating attacker-chosen JavaScript.

Source published

30 Sep 2026 01:47:59 UTC

Source modified

30 Sep 2026 03:00:04 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

OSV · upstream source license applies

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · OSV · upstream source license applies. Source text is retained; field grouping and change labels are provided by ChangeIntel.