CVE-2026-16516

9.0 CRITICAL 0.2% exploit odds Fix listed Other

What it 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).

At a glance

Exploitability: Can be exploited over the network without logging in. High risk of data tampering.
Exploit odds: 0.2% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2026-07-21 22:09 UTC ReservedThe CVE id was reserved by its CNA
2026-10-07 03:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-10-13 17:40 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.2% in the next 30 days (EPSS).
Severity: 9.0 CRITICAL (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2026-10-07 03:16 UTC
Last modified: 2026-10-13 17:40 UTC
Exploit probability: 0.2% · EPSS, next 30 days
Weakness: CWE-345
Record status: Analyzed

Affected

Wolfssh < 1.6.0

Attack profile CVSS 4.0 · 9.0

Attack vector: Network
Complexity: Low
Attack requirements: Present
Privileges needed: None
User interaction: None
Confidentiality: Low
Integrity: High
Availability: None

Raw 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/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

Is it in your code?

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Read https://cve-list.com/agent/cve/CVE-2026-16516.md and follow it. Check whether this project is affected by CVE-2026-16516. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record