Description
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).
Published: 2026-10-07
Score: 9 Critical
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

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History

Wed, 07 Oct 2026 12:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 07 Oct 2026 04:00:00 +0000

Type Values Removed Values Added
First Time appeared Wolfssl
Wolfssl wolfssh
Vendors & Products Wolfssl
Wolfssl wolfssh

Wed, 07 Oct 2026 02:45:00 +0000

Type Values Removed Values Added
Description 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).
Title wolfSSH ECDSA host key curve not validated against negotiated algorithm
Weaknesses CWE-345
References
Metrics cvssV4_0

{'score': 9, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:H/VA:N/SC:L/SI:H/SA:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: wolfSSL

Published:

Updated: 2026-10-07T11:17:14.029Z

Reserved: 2026-07-21T22:09:07.190Z

Link: CVE-2026-16516

cve-icon Vulnrichment

Updated: 2026-10-07T11:15:59.263Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-10-07T03:16:58.830

Modified: 2026-10-07T16:02:27.613

Link: CVE-2026-16516

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-07T04:00:10Z

Weaknesses