Which versions of @tostringtag/nsettostringtag are malicious?

The following npm versions of @tostringtag/nsettostringtag are flagged malicious: 99.9.9. Treat any of these as compromised.

How do I remediate @tostringtag/nsettostringtag if I installed it?

Remove @tostringtag/nsettostringtag 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 @tostringtag/nsettostringtag — how do I know if it already compromised me?

If @tostringtag/nsettostringtag 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 @tostringtag/nsettostringtag part of a known attack campaign?

Yes — @tostringtag/nsettostringtag is associated with the RLMA-2026-04791, RLUA-2026-05936 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 @tostringtag/nsettostringtag across my projects, lockfiles, and CI pipelines?

Search your lockfiles and build artifacts for @tostringtag/nsettostringtag (version 99.9.9).

Malicious package

@tostringtag/nsettostringtagnpm

Advisory published Jul 7, 2026Updated Sep 1, 2026

@tostringtag/nsettostringtag is a confirmed malicious npm package (MAL-2026-7097) that executes malicious code on install (malicious version 99.9.9). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in @tostringtag/nsettostringtag (npm)

MAL-2026-7097

Immediate action

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

npm uninstall @tostringtag/nsettostringtag

Malicious versions

1 flagged

99.9.9

Indicators of compromise (SHA-256)

0041ac6f8c0e0c85e57f9b4f18c2260f96bb0a0c75df642ffea0ad50853224a6

5b4d0e3df5630c83efa8e0387bbe6027c13134f62a31b72aad378998cbaa2f15

Detection & response playbook

Malicious package

Find it
Search your lockfiles and build artifacts for @tostringtag/nsettostringtag (version 99.9.9).
If you installed it — respond
Remove @tostringtag/nsettostringtag 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 @tostringtag/nsettostringtag 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. @tostringtag/nsettostringtag on npm has been identified as a malicious package (version 99.9.9 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

RLMA-2026-04791RLUA-2026-05936

References

github.com

Credits

ReversingLabs · finder

Detect & block this

O3 blocks @tostringtag/nsettostringtag-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

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