ed25519-dalek Double Public Key Signing Function Oracle Attack

Exploitation

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

CVSS

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

EPSS

• CVE-2022-50237: 0.22% estimated exploitation activity in the next 30 days; percentile 12.25 (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.

Versions of ed25519-dalek prior to v2.0 model private and public keys as separate types which can be assembled into a Keypair, and also provide APIs for serializing and deserializing 64-byte private/public keypairs. Such APIs and serializations are inherently unsafe as the public key is one of the inputs used in the deterministic computation of the S part of the signature, but not in the R value. An adversary could somehow use the signing function as an oracle that allows arbitrary public keys as input can obtain two signatures for the same message sharing the same R and only differ on the S part. Unfortunately, when this happens, one can easily extract the private key. Revised public APIs in v2.0 of ed25519-dalek do NOT allow a decoupled private/public keypair as signing input, except as part of specially labeled "hazmat" APIs which are clearly labeled as being dangerous if misused.

Published by the source

14 Aug 2023, 21:10 UTC

Last modified by the source

28 Jul 2025, 15:53 UTC

Source last checked

26 Oct 2026, 15:39 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-w5vr-6qhr-36cc

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# Patch Next advisory brief: CVE-2022-50237

Advisory: `ed25519-dalek` Double Public Key Signing Function Oracle Attack
IDs: CVE-2022-50237, GHSA-w5vr-6qhr-36cc
Record: https://patchnext.com/advisories/cve-2022-50237 (revision 1, source checked 26 Oct 2026, 15:39 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: ed25519-dalek 2.0.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io ed25519-dalek: affected < 2.0.0; fixed in 2.0.0

## Suggested inspection (read-only)
- crates.io ed25519-dalek: check the installed version with your package manager.

## 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 ed25519-dalek.
- 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-w5vr-6qhr-36cc (GitHub-reviewed advisory GHSA-w5vr-6qhr-36cc lists affected ranges: crates.io ed25519-dalek >=0 <2.0.0)

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