prettier_v1npm
Advisory published Updated
prettier_v1 is a confirmed malicious npm package (MAL-2026-5845) that typosquats a legitimate package to trick installs (malicious versions 3.8.4, 3.8.5). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in prettier_v1 (npm)
What this malware does
Package name 'prettier_v1' closely resembles the widely-used 'prettier' formatter package, a classic typosquat naming pattern. The file lib/mirror.js contains a Buffer.from(..., 'base64').toString('utf8') decode primitive at line 16, which is commonly used to obscure embedded payloads. Tracing of the decoded content and its downstream use (whether it is passed to eval/exec, written to disk, or executed) was not completed, so the actual installer-side impact has not been confirmed. The combination of a typosquat-shaped name plus a base64 decode in a file named 'mirror.js' warrants human review before this package is allowed into installer environments.
Any computer that has this package installed or running should be considered fully compromised. All secrets and keys stored on that computer should be rotated immediately from a different computer. The package should be removed, but as full control of the computer may have been given to an outside entity, there is no guarantee that removing the package will remove all malicious software resulting from installing it.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
TyposquatFind it
Search your lockfiles and build artifacts for prettier_v1 (2 malicious versions).
If you installed it — respond
prettier_v1 is a typosquat — you almost certainly intended a legitimately-named package. Remove prettier_v1, 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 prettier_v1 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
Campaign
References
Credits
- Amazon Inspector · finder
- ReversingLabs · finder
Detect & block this
O3 blocks prettier_v1-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.