Which versions of semer are malicious?

The following PyPI versions of semer are flagged malicious: 1.0.0. Treat any of these as compromised.

How do I remediate semer if I installed it?

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

If semer 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 semer part of a known attack campaign?

Yes — semer is associated with the 2026-10-semvver 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 semer across my projects, lockfiles, and CI pipelines?

Search your lockfiles and build artifacts for semer (version 1.0.0).

Part of a larger attack: 2026-10-semvver published 10 malicious packages. See the full campaign →

Malicious package

semerPyPI

Advisory published Oct 20, 2026Updated Oct 22, 2026

semer is a confirmed malicious PyPI package (MAL-2026-18118) that steals credentials and exfiltrates sensitive data (malicious version 1.0.0). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in semer (PyPI)

MAL-2026-18118

Immediate action

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

pip uninstall semer

What this malware does

During installation, package downloads and executes malware.

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

Campaign: 2026-10-semvver

Reasons (based on the campaign):

Downloads and executes a remote executable.
malware
typosquatting

Malicious versions

1 flagged

1.0.0

Indicators of compromise (SHA-256)

7479f42de6f963e39b7aa1409b586e605dca69978763ab35236d20c9126aa4f1

77a83c900954eea717ed30c2ec5f6e51b1b0b4a9591409845af5eadce09f4dfb

Detection & response playbook

Credential / info stealer

Find it
Search your lockfiles and build artifacts for semer (version 1.0.0).
If you installed it — respond
semer 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 semer 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. semer on PyPI has been identified as a malicious package (version 1.0.0 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

2026-10-semvver

References

Credits

Kamil Mańkowski (kam193) · reporter

Detect & block this

O3 blocks semer-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