WolfSSL WolfSSH up to 1.5.0 ECDSA Key Validation src/internal.c ParseECCPubKey pubKeyId input validation

Summaryinfo

A vulnerability classified as critical has been found in WolfSSL WolfSSH up to 1.5.0. This affects the function ParseECCPubKey of the file src/internal.c of the component ECDSA Key Validation. This manipulation of the argument pubKeyId causes input validation. The identification of this vulnerability is CVE-2026-16516. It is possible to initiate the attack remotely. There is no exploit available.

Detailsinfo

A vulnerability was found in WolfSSL WolfSSH up to 1.5.0. It has been declared as critical. Affected by this vulnerability is the function ParseECCPubKey of the file src/internal.c of the component ECDSA Key Validation. The manipulation of the argument pubKeyId with an unknown input leads to a input validation vulnerability. The CWE definition for the vulnerability is CWE-20. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

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).

The advisory is shared at github.com. This vulnerability is known as CVE-2026-16516 since 07/22/2026. The exploitation appears to be easy. The attack can be launched remotely. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 10/07/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-94161). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Vendor

• WolfSSL

Name

• WolfSSH

Version

• 1.0
• 1.1
• 1.2
• 1.3
• 1.4
• 1.5.0

License

• open-source

Website

• Product: https://github.com/wolfSSL/wolfssh/

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Entryinfo

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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