CVE-2026-128087
Deferred
Deferred - Pending Action
SSH Agent Key Exchange Flaw in Russh Library
Vulnerability report for CVE-2026-128087, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-11-13
Last updated on: 2026-11-13
Assigner: GitHub, Inc.
Description
Description
russh is a Rust SSH client and server library that includes an SSH agent protocol implementation. From version 0.55.0 until version 0.65.1, the initial key exchange invokes client::Handler::kex_done() with the raw shared secret before check_server_key() accepts the server host key or certificate. A malicious SSH server can therefore trigger application-defined secondary-channel initialization or early data handling even when the server identity is subsequently rejected. Ordinary clients that keep the callback's no-op default or independently defer callback-derived actions until trust is confirmed are not affected. This issue is fixed in version 0.65.1.
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
Currently, no data is known.
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-863 | The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. |
| CWE-696 | The product performs multiple related behaviors, but the behaviors are performed in the wrong order in ways that may produce resultant weaknesses. |
