CVE-2026-16516
wolfSSH ECDSA host key curve not validated against negotiated algorithm
No known exploitation. EPSS puts it in the 2nd percentile. Fixed in 1.6.0.
What to do
Find your product and version, then upgrade to the build on the right.
- wolfSSL Inc. wolfSSHAffected: ≤ 1.5.0Upgrade to: after 1.5.0Stated by: CVE record
- WolfsshAffected: < 1.6.0Upgrade to: 1.6.0Stated by: NVD
Versions as the sources state them. Full version matrix after sign-in
What it is
From the CVE record
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).
In plain language
No plain-language summary for this CVE yet.
Exploitation
Where each signal puts this CVE on the scale from published to confirmed exploited.
- CISA KEV
Not in the catalog. CISA has not confirmed exploitation.
- Public exploits
No public exploit or proof of concept found in the sources we track.
- EPSS
0.1% chance of exploitation activity in the next 30 days, which ranks it in the 2nd percentile of scored CVEs.
Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.
- Attention now
Rising, driven by in-the-wild reports.
Lifecycle
9 events over 6 days, from the signal feeds we watch.
- Patch availableworkaround available, record updated
- Publishedweakness classified, att&ck mapped, record updated, record updated, record updated
Affected products
Technical detail
CVSS 3.1 vector
Open in the CVSS calculatorCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Scored 7.4 by NVD.
How it is reached
- Attack Vector NetworkExploitable remotely over the network without any special conditions
- Attack Complexity HighRequires specific conditions like a race condition or non-default configuration
- Privileges Required NoneNo authentication required — anyone can exploit this
- User Interaction NoneNo user interaction needed — fully automated exploitation
Scope
- Scope UnchangedImpact is limited to the vulnerable component itself
Impact if exploited
- Confidentiality HighTotal information disclosure — all data in the component is compromised
- Integrity HighTotal loss of integrity — attacker can modify any data in the component
- Availability NoneNo availability impact
Weaknesses
ATT&CK techniques
Mapped from the weaknesses above (CWE to ATT&CK), not observed in attacks.
Sources
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