Which versions of marshmellow are malicious?

The following PyPI versions of marshmellow are flagged malicious: 1.0.0, 1.1.0. Treat any of these as compromised.

How do I remediate marshmellow if I installed it?

marshmellow is a typosquat — you almost certainly intended a legitimately-named package. Remove marshmellow, install the correct package, and rotate any secrets exposed during the install since post-install scripts may have already run.

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

If marshmellow 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 marshmellow part of a known attack campaign?

Yes — marshmellow is associated with the GENERIC-local-typosquatting 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 marshmellow 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 marshmellow (2 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging marshmellow across your stack and pipelines.

Malicious package

marshmellowPyPI

Malicious code in marshmellow (PyPI) Remove it immediately and rotate any exposed credentials.

MAL-2026-864

Immediate action

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

pip uninstall marshmellow

What this malware does

Package is a typosquatting or dependency confusion attempt with a low-harm local-only action, like leaving a flag file.

Category: PROBABLY_PENTEST - Packages looking like typical pentest packages, but also anything that looks like testing, exploring pre-prepared kits, research & co, with clearly low-harm possibilities.

Campaign: GENERIC-local-typosquatting

Reasons (based on the campaign):

dependency-confusion
The package overrides the install command in setup.py to execute malicious code during installation.
typosquatting

The OpenSSF Package Analysis project identified 'marshmellow' @ 1.1.0 (pypi) as malicious.

It is considered malicious because:

The package executes one or more commands associated with malicious behavior.

Malicious versions

2 flagged

1.0.01.1.0

Indicators of compromise (SHA-256)

dbf6f50353e6489a831a2575831b93fd5f99a9cbd60cc30260fd13838beda73f

385a79bb53771282b64601f5a3b17f0d7a3d735efbf863584f0dd2755bc2bf08

f4aaf04cc47fc8c3690dc509c889e05ca1a17673a00bf32579c76b629c6b58c5

Detection & response playbook

Typosquat

Find it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for marshmellow (2 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging marshmellow across your stack and pipelines.
If you installed it — respond
marshmellow is a typosquat — you almost certainly intended a legitimately-named package. Remove marshmellow, install the correct package, and rotate any secrets exposed during the install since post-install scripts may have already run.
Did it already run?
If marshmellow 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 marshmellow 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. marshmellow on PyPI has been identified as a malicious package (versions 1.0.0, 1.1.0 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

GENERIC-local-typosquatting

References

bad-packages.kam193.eu

Credits

Kamil Mańkowski (kam193) · reporter
OpenSSF: Package Analysis · finder

Detect & block this

O3 blocks marshmellow-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