Which versions of workcalender are malicious?

The following PyPI versions of workcalender are flagged malicious: 17.1.0.dev0. Treat any of these as compromised.

How do I remediate workcalender if I installed it?

workcalender 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 workcalender — how do I know if it already compromised me?

If workcalender 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.

Is workcalender part of a known attack campaign?

Yes — workcalender is associated with the 2026-10-test-workalendar-internal 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 workcalender across my projects, lockfiles, and CI pipelines?

Search your lockfiles and build artifacts for workcalender (version 17.1.0.dev0).

Malicious package

workcalenderPyPI

Advisory published Oct 20, 2026Updated Oct 20, 2026

workcalender is a confirmed malicious PyPI package (MAL-2026-18093) that steals credentials and exfiltrates sensitive data (malicious version 17.1.0.dev0). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in workcalender (PyPI)

MAL-2026-18093

Immediate action

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

pip uninstall workcalender

What this malware does

This package contains a stub build-time helper, which in another package of the same uploader was already turned into a backdoor installation. While this package does not yet contain malicious code, it is clear it was uploaded with such intention and likely exploits dependency confusion.

Category: MALICIOUS - The campaign has clearly malicious intent, like infostealers.

Campaign: 2026-10-test-workalendar-internal

Reasons (based on the campaign):

backdoor
The package overrides the install command in setup.py to execute malicious code during installation.

Malicious versions

1 flagged

17.1.0.dev0

Indicators of compromise (SHA-256)

9a336c0fa7a5b3ee5f036d678c8c0f0d549135a08d05549ee92cb11b1a7f78fa

Detection & response playbook

Credential / info stealer

Find it
Search your lockfiles and build artifacts for workcalender (version 17.1.0.dev0).
If you installed it — respond
workcalender 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 workcalender 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

No. workcalender on PyPI has been identified as a malicious package (version 17.1.0.dev0 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

2026-10-test-workalendar-internal

References

bad-packages.kam193.eu

Credits

Kamil Mańkowski (kam193) · reporter

Detect & block this

O3 blocks workcalender-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

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