---
id: CVE-2026-16516
title: >-
  wolfSSH does not validate that the ECDSA curve identifier in a KEXDH_REPLY
  host key blob matches the algorithm negotiated during key exchange
summary: >-
  wolfSSH does not validate that the ECDSA curve identifier in a KEXDH_REPLY
  host key blob matches the algorithm negotiated during key exchange. In
  ParseECCPubKey() (src/internal.c), the blob's algorithm string is used to
  derive the curve …
severity: high
cvss: 7.4
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N'
cwe:
  - CWE-345
vendor: wolfssh
product: wolfssh
affected:
  - wolfssh < 1.6.0
patched:
  - wolfssh 1.6.0
published: '2026-10-07'
updated: '2026-10-13'
sourceUpdated: '2026-10-13T17:40:07.413'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-16516'
references:
  - url: >-
      https://github.com/wolfSSL/wolfssh/commit/31d13697a608fa1bf9eec11aa6eff1503ade836f
    label: facts@wolfssl.com
  - url: 'https://github.com/wolfSSL/wolfssh/issues/1012'
    label: facts@wolfssl.com
tags:
  - nvd
  - cve.org
epss: 0.00191
epssPercentile: 0.08651
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-10-07T11:15:50.612166Z'
scores:
  nvd: 7.4
  cna: 9
ingestedAt: '2026-10-07T03:28:55.181Z'
---

## Overview

wolfSSH does not validate that the ECDSA curve identifier in a KEXDH_REPLY host key blob matches the algorithm negotiated during key exchange. In ParseECCPubKey() (src/internal.c), the blob's algorithm string is used to derive the curve via NameToId/wcPrimeForId without checking against the negotiated ssh->handshake->pubKeyId, and the RFC 5656 curve identifier string is discarded via GetSkip() rather than compared. An active network man-in-the-middle attacker can substitute a host key blob containing a different ECDSA curve, causing the client to import the key on the wrong curve. Because the attacker controls the private key for the substituted curve, signature verification passes. Exploitation requires an active MitM position and a lax public key check callback (e.g., TOFU, algorithm-name-only check, or fingerprint match against the parsed key).

## Affected

- `wolfssh < 1.6.0`

## Remediation

Upgrade past the affected range:

- `wolfssh 1.6.0`