Elliptic's private key extraction in ECDSA upon signing a malformed input (e.g. a string)

Exploitation

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

CVSS 4.0

9.0 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:H/SA:N · score source

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Summary Private key can be extracted from ECDSA signature upon signing a malformed input (e.g. a string or a number), which could e.g. come from JSON network input Note that elliptic by design accepts hex strings as one of the possible input types Details In this code: https://github.com/indutny/elliptic/blob/3e46a48fdd2ef2f89593e5e058d85530578c9761/lib/elliptic/ec/index.js#L100-L107 msg is a BN instance after conversion, but nonce is an array, and different BN instances could generate equivalent arrays after conversion. Meaning that a same nonce could be generated for different messages used in signing process, leading to k reuse, leading to private key extraction from a pair of signatures Such a message can be constructed for any already known message/signature pair, meaning that the attack needs only a single malicious message being signed for a full key extraction While signing unverified attacker-controlled messages would be problematic itself (and exploitation of this needs…

Published by the source

12 Feb 2025, 19:47 UTC

Last modified by the source

23 Feb 2025, 23:30 UTC

Source last checked

26 Oct 2026, 12:36 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-vjh7-7g9h-fjfh

2. Revision 2 · amended · 25 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-vjh7-7g9h-fjfh

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# Patch Next advisory brief: GHSA-vjh7-7g9h-fjfh

Advisory: Elliptic's private key extraction in ECDSA upon signing a malformed input (e.g. a string)
IDs: GHSA-vjh7-7g9h-fjfh
Record: https://patchnext.com/advisories/ghsa-vjh7-7g9h-fjfh (revision 3, source checked 26 Oct 2026, 12:36 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.0)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: elliptic 6.6.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm elliptic: affected <= 6.6.0; fixed in 6.6.1

## Suggested inspection (read-only)
- `npm ls elliptic --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 elliptic.
- 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-vjh7-7g9h-fjfh (OSV record GHSA-vjh7-7g9h-fjfh lists affected ranges: npm elliptic >=0 <6.6.1 (fixed))
- Verified: https://github.com/advisories/GHSA-vjh7-7g9h-fjfh (GitHub-reviewed advisory GHSA-vjh7-7g9h-fjfh lists affected ranges: npm elliptic >=0 <=6.6.0)

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