Malicious Package in flatmap-stream

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

9.8 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Version 0.1.1 of flatmap-stream is considered malicious. This module runs an encrypted payload targeting a very specific application, copay and because they shared the same description it would have likely worked for copay-dash. The injected code: - Read in AES encrypted data from a file disguised as a test fixture - Grabbed the npm package description of the module that imported it, using an automatically set environment variable - Used the package description as a key to decrypt a chunk of data pulled in from the disguised file The decrypted data was part of a module, which was then compiled in memory and executed. This module performed the following actions: - Decrypted another chunk of data from the disguised file - Concatenated a small, commented prefix from the first decrypted chunk to the end of the second decrypted chunk - Performed minor decoding tasks to transform the concatenated block of code from invalid JS to valid JS (we believe this was done to evade detection by…

Published by the source

1 Sep 2020, 21:21 UTC

Last modified by the source

9 Jan 2023, 05:03 UTC

Source last checked

26 Oct 2026, 12:09 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-9x64-5r7x-2q53

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-9x64-5r7x-2q53

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# Patch Next advisory brief: GHSA-9x64-5r7x-2q53

Advisory: Malicious Package in flatmap-stream
IDs: GHSA-9x64-5r7x-2q53
Record: https://patchnext.com/advisories/ghsa-9x64-5r7x-2q53 (revision 2, source checked 26 Oct 2026, 12:09 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm flatmap-stream: affected >= 0.1.1, <= 0.1.1

## Suggested inspection (read-only)
- `npm ls flatmap-stream --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on flatmap-stream.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-9x64-5r7x-2q53 (OSV record GHSA-9x64-5r7x-2q53 lists affected ranges: npm flatmap-stream >=0.1.1 <=0.1.1)
- Verified: https://github.com/advisories/GHSA-9x64-5r7x-2q53 (GitHub-reviewed advisory GHSA-9x64-5r7x-2q53 lists affected ranges: npm flatmap-stream >=0.1.1 <=0.1.1)

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