Wolfssh: >> Wolfssh >> 0.2.0 Security Vulnerabilities
In wolfSSH through 1.5.0 built with --enable-fwd, DoChannelOpen() in src/internal.c gates only direct-tcpip channel opens with the forwarding policy callback. forwarded-tcpip opens are admitted without an authorization check and are not capped in number, allowing a malicious SSH peer to make an endpoint allocate unbounded per-channel buffers for forwarding channels the application never authorized. A client also does not check a forwarded-tcpip open against the forwards it registered with a tcpip-forward request, as RFC 4254 section 7.2 requires, so a malicious server can open forwarding channels for addresses and ports the client never asked it to forward.
CVSS Score
6.3
EPSS Score
0.003
Published
2026-10-07
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).
CVSS Score
9.0
EPSS Score
0.002
Published
2026-10-07
wolfSSH’s key exchange state machine can be manipulated to leak the client’s password in the clear, trick the client to send a bogus signature, or trick the client into skipping user authentication. This affects client applications with wolfSSH version 1.4.21 and earlier. Users of wolfSSH must update or apply the fix patch and it’s recommended to update credentials used. This fix is also recommended for wolfSSH server applications. While there aren’t any specific attacks on server applications, the same defect is present. Thanks to Aina Toky Rasoamanana of Valeo and Olivier Levillain of Telecom SudParis for the report.
CVSS Score
9.4
EPSS Score
0.004
Published
2026-01-06
Improper host authentication vulnerability in wolfSSH version 1.4.20 and earlier clients that allows authentication bypass and leaking of clients credentials.
CVSS Score
9.4
EPSS Score
0.004
Published
2025-10-21
A vulnerability was found in wolfSSH's server-side state machine before versions 1.4.17. A malicious client could create channels without first performing user authentication, resulting in unauthorized access.
CVSS Score
9.1
EPSS Score
0.006
Published
2024-03-25