{"answers":{"affected":"1 open source package ship an affected version, including chai-plugin-helper.","exploited":"There is no known exploitation of MAL-2026-5905 in the wild and no public exploit code.","fix":"Remove the package from your dependencies and lockfiles, then rotate any secrets on machines where it was installed.","what":"MAL-2026-5905 is a malicious package in chai-plugin-helper, published on 16 Jun 2026."},"fix_prompt":"MAL-2026-5905 is a malicious package: chai-plugin-helper (npm). Every version was published to cause harm.\n\nTask:\n1. Search this repository's dependency manifests and lockfiles for the package, including transitive dependencies.\n2. If it is present, remove it, regenerate the lockfile with the project's package manager, and replace whatever it was used for.\n3. List any CI runners, developer machines or containers that installed it, so their secrets can be rotated.\n4. If the package is not used anywhere, say so and change nothing.\n\nReference: https://insights.sbomify.com/MAL-2026-5905/ (Markdown: https://insights.sbomify.com/MAL-2026-5905/index.md)","id":"MAL-2026-5905","markdown":"https://insights.sbomify.com/MAL-2026-5905/index.md","name":"MAL-2026-5905","record":{"aliases":[],"analysis":null,"analysis_generated_by":null,"assigner":null,"cpe":[],"cvss":{"score":null,"severity":null,"source":null,"vector":null,"version":null},"cwes":[],"description":"chai-plugin-helper poses as a chai plugin and ships a verbatim copy of chai's public API (index.js, lib/chai.js, expect/should/assert exports, version string '4.3.8', description copied from chai) so it functions as a drop-in replacement. On require('chai-plugin-helper'), index.js line 8 spawns a detached background `node` process that runs lib/chai/utils/assertion.js: `const child = spawn(\"node\", [assertion, JSON.stringify(args)], { detached: true, stdio: \"ignore\" })`. assertion.js is obfuscator.io-encoded with a rotated 31-entry string array decoded via a base64+URI-decode chain and hex-named identifiers (_0x479d3b, _0x4a30, etc.). After deobfuscation, the file performs an HTTP(S) GET to a URL built from the encoded constants and passes the response body into `new Function(_0x154837[...],_0x375b9e)` invoked with the installer's `require` — executing attacker-controlled remote code with full Node privileges. The copyright header has been altered to 'Anton Lane' while the rest of chai's source is copied verbatim, so installers see a working assertion library and do not notice the dropper running in the background. Combination of namespace impersonation, drop-in API, obfuscation specifically wrapping the fetch+exec path, and remote-code execution at require-time is unambiguous supply-chain attack.","ecosystems":["npm"],"exploits":{"exploitdb":null,"first_seen":null,"github_poc":null,"max_poc_stars":null,"metasploit":null,"nuclei":null,"refs":[],"tier":null},"has_fix":false,"headline":"Malicious code in chai-plugin-helper (npm)","id":"MAL-2026-5905","indexable":true,"kev":null,"kind":"malicious","links":{"ecosystem":"npm","product":null,"products":[],"type":null,"year":"2026"},"n_packages":1,"n_references":null,"packages":[{"ecosystem":"npm","fixed":[],"introduced":[],"last_affected":[],"package":"chai-plugin-helper","purl":"pkg:npm/chai-plugin-helper","source":"MAL-2026-5905"}],"products":null,"published":"2026-06-16","related":[],"sources":[{"class":"attribution","licence":"Apache-2.0","name":"OpenSSF Malicious Packages","prefix":"MAL"}],"ssvc":{"automatable":null,"exploitation":null,"technical_impact":null},"state":null,"updated":null,"vendors":null},"summary":null,"url":"https://insights.sbomify.com/MAL-2026-5905/"}