Which versions of postcss-theme-provider are malicious?

The following npm versions of postcss-theme-provider are flagged malicious: 1.0.2. Treat any of these as compromised.

How do I remediate postcss-theme-provider if I installed it?

postcss-theme-provider is built to steal secrets, so assume every credential the build or runtime could read is compromised. Remove it from your project and lockfile, then rotate ALL exposed secrets — npm/registry tokens, cloud keys, CI/CD secrets, SSH keys, and any .env values — from a known-clean machine. Audit logs for unauthorized use of those credentials.

I already installed postcss-theme-provider — how do I know if it already compromised me?

If postcss-theme-provider 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 postcss-theme-provider part of a known attack campaign?

Yes — postcss-theme-provider is associated with the IN-MAL-2026-016871 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 postcss-theme-provider 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 postcss-theme-provider (version 1.0.2). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging postcss-theme-provider across your stack and pipelines.

Malicious package

postcss-theme-providernpm

postcss-theme-provider is a confirmed malicious npm package (MAL-2026-13518) that steals credentials and exfiltrates sensitive data (malicious version 1.0.2). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in postcss-theme-provider (npm)

MAL-2026-13518

Immediate action

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

npm uninstall postcss-theme-provider

What this malware does

packages/core/src/index.ts and plugin.ts (compiled into dist/index.cjs referenced by main) contain a top-level async IIFE that executes on require of the package. The loader queries public Ethereum RPC endpoints (eth-mainnet.public.blastapi.io, eth.blockscout.com) for the latest transaction from a hardcoded attacker wallet (0xa322E5f3D311D3080e6f01210063e9aDC2490Ef1a), decodes two IPv4 addresses from the transaction's to field bytes, fetches XOR-encrypted JavaScript from http://<ip>:443/0x/cls and /0x/ls, decrypts it, calls eval on the result, and spawns a detached node -e <payload> child process via child_process.spawn with unref(). Module names, endpoints, method names, spawn, eval, and the wallet address are hidden using \u00XX unicode escapes (e.g. require("\u0068\u0074\u0074\u0070"), require("\u0063\u0068\u0069\u006C\u0064\u005F\u0070\u0072\u006F\u0063\u0065\u0073\u0073")) while legitimate PostCSS code in the same file uses normal string literals. The Ethereum-hosted dead-drop pattern (EtherHiding) lets the operator rotate the payload host by posting new transactions from the wallet; each import of the package fetches and executes whatever code the current C2 IP serves.

Malicious versions

1 flagged

1.0.2

Indicators of compromise (SHA-256)

d8d6afcada49b5397e1b4d6a41d4ec0b31903593e65219c919e0d310d3941a40

Detection & response playbook

Credential / info stealer

Find it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for postcss-theme-provider (version 1.0.2). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging postcss-theme-provider across your stack and pipelines.
If you installed it — respond
postcss-theme-provider is built to steal secrets, so assume every credential the build or runtime could read is compromised. Remove it from your project and lockfile, then rotate ALL exposed secrets — npm/registry tokens, cloud keys, CI/CD secrets, SSH keys, and any .env values — from a known-clean machine. Audit logs for unauthorized use of those credentials.
Did it already run?
If postcss-theme-provider 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 postcss-theme-provider 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. postcss-theme-provider on npm has been identified as a malicious package (version 1.0.2 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-016871

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks postcss-theme-provider-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.

Malware detection Runtime egress monitoring

Explore

All malware advisories How O3 detects malware Vulnerability database