Which versions of fastavro are malicious?

Every published version of fastavro on npm is considered malicious. Remove the package entirely.

How do I remediate fastavro if I installed it?

Remove fastavro from your project and lockfile, then assume any secrets accessible to the build or runtime were exposed: rotate API keys, tokens, and credentials, and audit for unexpected outbound activity or persistence.

I already installed fastavro — how do I know if it already compromised me?

If fastavro 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 fastavro part of a known attack campaign?

Yes — fastavro is associated with the GHSA-85hv-887w-rf37 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 fastavro 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 fastavro (all published versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging fastavro across your stack and pipelines.

Malicious package

fastavronpm

Malicious code in fastavro (npm) Remove it immediately and rotate any exposed credentials.

MAL-2025-192411

Immediate action

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

npm uninstall fastavro

What this malware does

The package fastavro was found to contain malicious code.

Any computer that has this package installed or running should be considered fully compromised. All secrets and keys stored on that computer should be rotated immediately from a different computer. The package should be removed, but as full control of the computer may have been given to an outside entity, there is no guarantee that removing the package will remove all malicious software resulting from installing it.

Malicious versions

all versions

Every published version of this package is considered malicious — remove it entirely.

Indicators of compromise (SHA-256)

dfa83913e0a60ce0006e336f2f9f837aac0fa16d414d3c4c149562e19aed7474

b8e01c7f0d2603f1d6cf541b7aa69c4bf9253ad1cd6b970a3337db957668a420

Detection & response playbook

Malicious package

Find it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for fastavro (all published versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging fastavro across your stack and pipelines.
If you installed it — respond
Remove fastavro from your project and lockfile, then assume any secrets accessible to the build or runtime were exposed: rotate API keys, tokens, and credentials, and audit for unexpected outbound activity or persistence.
Did it already run?
If fastavro 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 fastavro 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. fastavro on npm has been identified as a malicious package (all published versions flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

GHSA-85hv-887w-rf37

References

github.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks fastavro-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the malicious outbound activity and severs the channel.

Malware detection Runtime egress monitoring