Insecure random number generation in keypair

Exploitation

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

CVSS

8.7 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N

EPSS

• CVE-2021-41117: 3.19% estimated exploitation activity in the next 30 days; percentile 88.11 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Description and Impact A bug in the pseudo-random number generator used by keypair versions up to and including 1.0.3 could allow for weak RSA key generation. This could enable an attacker to decrypt confidential messages or gain authorized access to an account belonging to the victim. We recommend replacing any RSA keys that were generated using keypair version 1.0.3 or earlier. Fix The bug in the pseudo-random number generator is fixed in commit 9596418. If the crypto module is available, it is used instead of the pseudo-random number generator. Also fixed in 9596418 Additional Details The specific line with the flaw is: The definition of putByte is Simplified, this is String.fromCharCode(String.fromCharCode(next & 0xFF)). This results in most of the buffer containing zeros. An example generated buffer: (Note: truncated for brevity) Since it is masking with 0xFF, approximately 97% of the bytes are converted to zeros. The impact is that each byte in the RNG seed has a 97% chance of…

Published by the source

11 Oct 2021, 17:09 UTC

Last modified by the source

8 Jul 2026, 06:27 UTC

Source last checked

26 Oct 2026, 12:21 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-3f99-hvg4-qjwj

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-3f99-hvg4-qjwj

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# Patch Next advisory brief: CVE-2021-41117

Advisory: Insecure random number generation in keypair
IDs: CVE-2021-41117, GHSA-3f99-hvg4-qjwj
Record: https://patchnext.com/advisories/cve-2021-41117 (revision 2, source checked 26 Oct 2026, 12:21 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: keypair 1.0.4. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm keypair: affected < 1.0.4; fixed in 1.0.4

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

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on keypair.
- 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-3f99-hvg4-qjwj (OSV record GHSA-3f99-hvg4-qjwj lists affected ranges: npm keypair >=0 <1.0.4 (fixed))
- Verified: https://github.com/advisories/GHSA-3f99-hvg4-qjwj (GitHub-reviewed advisory GHSA-3f99-hvg4-qjwj lists affected ranges: npm keypair >=0 <1.0.4)

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