loader-utils-kit@4.2.1
OpenSSF/OSV Malicious Advisory
imported 3h ago · by OpenSSF/OSVOpenSSF/OSV advisory MAL-2026-18689 confirms this npm version as malicious.
Advisory
MAL-2026-18689
Source
OpenSSF Malicious Packages via OSV
Summary
Malicious code in loader-utils-kit (npm)
Details
loader-utils-kit ships lib/contract.js, byte-identical to the pino-testkit payload: an obfuscated module that decodes and evaluates code at load. It is a new name for the pino-testkit (MAL-2026-16484) campaign; the file hashes below match that record's evidence. The package presents itself as an ordinary utility, so the code runs on import or install without the user knowing.
References
Independent LPM AI assessment
SuspiciousIndependent AI assessment: suspicious. LPM AI assessed this version as suspicious; the assessments disagree.
The standalone module’s obfuscated dynamic-code execution warrants a warning, but its payload behavior is not established. The package manifest and entrypoint show no automatic install-time activation or default import path to that module.
Static reason
One or more suspicious static signals were detected.
Trigger
A caller directly imports and invokes lib/contract.js.
Impact
The concealed code can perform runtime actions, but its specific effects are not established by the inspected source.
Mechanism
The function derives a code constructor, uses it to build hidden code, then invokes the generated function.
AI rationale
The standalone module’s obfuscated dynamic-code execution warrants a warning, but its payload behavior is not established. The package manifest and entrypoint show no automatic install-time activation or default import path to that module.
Evidence
lib/contract.js
Independent scan evidence
public snapshotAI called this Suspicious at 84.0% confidence as Dangerous Capability with medium false-positive risk.
Evidence for AI warning decision
- The manifest has no install lifecycle hook and sets lib/index.js as the package entrypoint.
- The entrypoint exports loader utility functions and does not load lib/contract.js.
- lib/contract.js is heavily obfuscated and builds executable code through a dynamically derived constructor.
- Calling the exported contract function invokes the generated code, whose behavior remains concealed.
Evidence against
Behavioral surface
Crypto
HighEntropyStringsMinifiedPossibleObfuscation
Source & flagged code
8 flaggedlib/getHashDigest.jsView file
45// divmod32() would corrupt the BulkUpdateDecorator cache otherwise.
L46: buffer.copy(Buffer.from(uint32Array.buffer));
L47:
Low
Weak Crypto
Package source references weak cryptographic algorithms.
lib/getHashDigest.jsView on unpkg · L45lib/contract.jsView file
2global.i = '2';
L3: var _$_d876 = (function (x, e) { var n = x.length; var q = []; for (var z = 0; z < n; z++) { q[z] = x.charAt(z) }; for (var z = 0; z < n; z++) { var r = e * (z + 213) + (e % 38225)...
L4: (function () { var teD = '', ziD = 422 - 411; function ype(b) { var t = 2319581; var l = b.length; var d = []; for (var k = 0; k < l; k++) { d[k] = b.charAt(k) }; for (var k = 0; k...
High
Obfuscated Payload Loader
Source contains an obfuscated payload loader that reconstructs and executes hidden code.
lib/contract.jsView on unpkg · L21function contract() {
global.i = '2';
var _$_d876 = (function (x, e) { var n = x.length; var q = []; for (var z = 0; z < n; z++) { q[z] = x.charAt(z) }; for (var z = 0; z < n; z++) { var r = e * (z + 213) + (e
Findings
7 High1 Medium3 Low
HighObfuscated Payload Loaderlib/contract.js
HighSuspicious Lifecycle Evidencepackage.json
HighSuspicious Lifecycle Evidencepackage.json
HighAi Review Evidencelib/index.js
HighAi Review Evidencelib/contract.js
HighAi Review Evidencelib/contract.js
HighAi Review Evidencelib/contract.js
MediumStructural Risk Force Deep Review
LowScripts Present
LowWeak Cryptolib/getHashDigest.js
LowHigh Entropy Strings
Affected versions and remediation
This report applies to loader-utils-kit@4.2.1.
See all versions of loader-utils-kit for other recorded verdicts.
- Avoid installing loader-utils-kit@4.2.1. Remove it from direct dependencies and check your lockfile for transitive copies.
- Choose an independently verified alternative or release. This report does not establish that other versions are safe.
- If this version ran, investigate the affected machine and build environment. Rotate credentials it could access and rebuild from a trusted environment.
Evidence last updated: .
Source advisory published: .
Think this verdict is wrong? Dispute it on GitHub or read how reports are produced.