num2wordsPyPI
Advisory published Updated
num2words is a confirmed malicious PyPI package (MAL-2025-6794) that executes malicious code on install (malicious versions 0.5.15, 0.5.16). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in num2words (PyPI)
What this malware does
The num2words project was compromised via a phishing attack and two new versions were uploaded to PyPI containing malicious code. The affected versions have been removed from PyPI, and users are advised to remove the affected versions from their environments.
The num2words project was compromised via a phishing attack and two new versions were uploaded to PyPI containing malicious code.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Malicious packageFind it
Search your lockfiles and build artifacts for num2words (2 malicious versions).
If you installed it — respond
Remove num2words 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 num2words was installed, its post-install payload may already have run. Removing the package does not undo that — check outbound connections and credential use from the install window onward.
Frequently asked questions
Campaign
References
Detect & block this
O3 blocks num2words-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.