Which versions of epxresso are malicious?

The following npm versions of epxresso are flagged malicious: 5.1.0, 5.1.1, 5.1.2, 5.1.3. Treat any of these as compromised.

How do I remediate epxresso if I installed it?

Remove epxresso 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 epxresso — how do I know if it already compromised me?

If epxresso 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 epxresso part of a known attack campaign?

Yes — epxresso is associated with the RLMA-2025-04511, RLUA-2025-05780 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 epxresso across my projects, lockfiles, and CI pipelines?

Search your lockfiles and build artifacts for epxresso (4 malicious versions).

Malicious package

epxressonpm

Advisory published Aug 14, 2025Updated Dec 2, 2025

epxresso is a confirmed malicious npm package (MAL-2025-19729) that executes malicious code on install (malicious versions 5.1.0, 5.1.1, 5.1.2…). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in epxresso (npm)

MAL-2025-19729

Immediate action

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

npm uninstall epxresso

What this malware does

The package epxresso was found to contain malicious code.

Malicious versions

4 flagged

5.1.05.1.15.1.25.1.3

Indicators of compromise (SHA-256)

a4e189cbdba808b8cf52ec2f0bb137bebf0aa30e83f768486b0baae6154ee398

78743035bbaca745b03d0af646c055eb7ea169da0c2e6766a1edcf31721ea47e

Detection & response playbook

Malicious package

Find it
Search your lockfiles and build artifacts for epxresso (4 malicious versions).
If you installed it — respond
Remove epxresso 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 epxresso 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. epxresso on npm has been identified as a malicious package (versions 5.1.0, 5.1.1, 5.1.2, 5.1.3 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

RLMA-2025-04511RLUA-2025-05780

References

Credits

Amazon Inspector · finder
ReversingLabs · finder

Detect & block this

O3 blocks epxresso-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

Explore

All malware advisories How O3 detects malware Vulnerability database