{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-16516", "assignerOrgId": "50d2cd11-d01a-48ed-9441-5bfce9d63b27", "state": "PUBLISHED", "assignerShortName": "wolfSSL", "dateReserved": "2026-07-21T22:09:07.190Z", "datePublished": "2026-10-07T02:38:23.334Z", "dateUpdated": "2026-10-07T02:38:23.334Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "50d2cd11-d01a-48ed-9441-5bfce9d63b27", "shortName": "wolfSSL", "dateUpdated": "2026-10-07T02:38:23.334Z"}, "title": "wolfSSH ECDSA host key curve not validated against negotiated algorithm", "problemTypes": [{"descriptions": [{"lang": "en", "cweId": "CWE-345", "description": "CWE-345 Insufficient Verification of Data Authenticity", "type": "CWE"}]}], "impacts": [{"capecId": "CAPEC-475", "descriptions": [{"lang": "en", "value": "CAPEC-475 Signature Spoofing by Improper Validation"}]}], "affected": [{"vendor": "wolfSSL Inc.", "product": "wolfSSH", "repo": "https://github.com/wolfSSL/wolfssh", "programFiles": ["src/internal.c"], "versions": [{"status": "affected", "version": "0", "lessThanOrEqual": "1.5.0", "changes": [{"at": "1.6.0", "status": "unaffected"}], "versionType": "semver"}], "defaultStatus": "unaffected"}], "descriptions": [{"lang": "en", "value": "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).", "supportingMedia": [{"type": "text/html", "base64": false, "value": "wolfSSH does not validate that the ECDSA curve identifier in a KEXDH_REPLY host key blob matches the algorithm negotiated during key exchange. In <code>ParseECCPubKey()</code> (<code>src/internal.c</code>), the blob's algorithm string is used to derive the curve via <code>NameToId</code>/<code>wcPrimeForId</code> without checking against the negotiated <code>ssh-&gt;handshake-&gt;pubKeyId</code>, and the RFC 5656 curve identifier string is discarded via <code>GetSkip()</code> 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)."}]}], "references": [{"url": "https://github.com/wolfSSL/wolfssh/issues/1012", "name": "ECDSA host key curve substitution - blob curve not validated against negotiated algorithm", "tags": ["issue-tracking"]}, {"url": "https://github.com/wolfSSL/wolfssh/commit/31d13697a608fa1bf9eec11aa6eff1503ade836f", "tags": ["patch"]}], "metrics": [{"format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}], "cvssV4_0": {"attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "LOW", "subConfidentialityImpact": "LOW", "vulnIntegrityImpact": "HIGH", "subIntegrityImpact": "HIGH", "vulnAvailabilityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED", "version": "4.0", "baseSeverity": "CRITICAL", "baseScore": 9, "vectorString": "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"}}], "credits": [{"lang": "en", "value": "zhangph (GitHub afldl)", "type": "finder"}], "source": {"discovery": "EXTERNAL"}, "x_generator": {"engine": "Vulnogram 1.0.2"}}}}

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{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "wolfSSH", "programFiles": ["src/internal.c"], "repo": "https://github.com/wolfSSL/wolfssh", "vendor": "wolfSSL Inc.", "versions": [{"changes": [{"at": "1.6.0", "status": "unaffected"}], "lessThanOrEqual": "1.5.0", "status": "affected", "version": "0", "versionType": "semver"}]}], "source": "[email protected]"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "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)."}], "id": "CVE-2026-16516", "lastModified": "2026-10-07T03:16:58.830", "metrics": {"cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "attackVector": "NETWORK", "availabilityRequirement": "NOT_DEFINED", "baseScore": 9.0, "baseSeverity": "CRITICAL", "confidentialityRequirement": "NOT_DEFINED", "exploitMaturity": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "privilegesRequired": "NONE", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "LOW", "subIntegrityImpact": "HIGH", "userInteraction": "NONE", "valueDensity": "NOT_DEFINED", "vectorString": "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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "version": "4.0", "vulnAvailabilityImpact": "NONE", "vulnConfidentialityImpact": "LOW", "vulnIntegrityImpact": "HIGH", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "source": "[email protected]", "type": "Secondary"}]}, "published": "2026-10-07T03:16:58.830", "references": [{"source": "[email protected]", "url": "https://github.com/wolfSSL/wolfssh/commit/31d13697a608fa1bf9eec11aa6eff1503ade836f"}, {"source": "[email protected]", "url": "https://github.com/wolfSSL/wolfssh/issues/1012"}], "sourceIdentifier": "[email protected]", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-345"}], "source": "[email protected]", "type": "Secondary"}]}

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