Forge: Ed25519 signature verification accepts small-order public keys

Exploitation

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

CVSS

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

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Summary `ed25519.verify()` does not reject public keys of small order, such as the identity point. Under such a key, a signature with `S = 0` and a small-order `R` verifies for many messages, or for every message with the identity key, without any private key. Fixed in node-forge 1.4.3.

Details `crypto_sign_open()` in `lib/ed25519.js` decodes the public key `A` with `unpackneg()`, which only checks that the point is on the curve, and then checks `R == [S]B - [k]A` with `k = SHA-512(R || A || M)`. Nothing rejects public keys of small order: the identity point, the other 7 points of order 2, 4 or 8, and their non-canonical encodings with `y >= p`. With `S = 0`, the check becomes `R == k`. For a small-order `A`, `k` is one of at most 8 small-order points, so an attacker can make a valid signature by trying the small-order values of `R`. For the identity key (`01 00 … 00`), `R = identity` and `S = 0` verifies for every message. For the other small-order keys, a given…

Published by the source

10 Nov 2026, 21:18 UTC

Last modified by the source

10 Nov 2026, 21:30 UTC

Source last checked

11 Nov 2026, 06:00 UTC

1. Revision 2 · amended · 11 Nov 2026

   Amended from osv record GHSA-6889-vf6x-f3g5

2. Revision 1 · created · 10 Nov 2026

   Published from ghsa record GHSA-6889-vf6x-f3g5

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# Patch Next advisory brief: CVE-2026-125335

Advisory: Forge: Ed25519 signature verification accepts small-order public keys
IDs: CVE-2026-125335, GHSA-6889-vf6x-f3g5
Record: https://patchnext.com/advisories/cve-2026-125335 (revision 2, source checked 11 Nov 2026, 06:00 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 3.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: node-forge 1.4.3. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm node-forge: affected < 1.4.3; fixed in 1.4.3

## Suggested inspection (read-only)
- `npm ls node-forge --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 node-forge.
- 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://github.com/advisories/GHSA-6889-vf6x-f3g5 (GitHub-reviewed advisory GHSA-6889-vf6x-f3g5 lists affected ranges: npm node-forge >=0 <=1.4.2)
- Verified: https://osv.dev/vulnerability/GHSA-6889-vf6x-f3g5 (OSV record GHSA-6889-vf6x-f3g5 lists affected ranges: npm node-forge >=0 <1.4.3 (fixed))

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