CVE-2026-128087
russh kex_done: shared-secret callback runs before server host-key verification
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.
Fixes and workarounds
Fix
russh (crates.io): OSV reports a fixed version 0.65.1. Check the advisory for supported release branches.
Source: OSV GHSA-9264-jvgf-6w2fAffected products and versions
| Product | Versions | Authority |
|---|---|---|
| russh Eugeny |
>= 0.55.0, < 0.65.1 (affected) | CNA: GitHub_M |
russhrussh
crates.io |
≥ 0.55.0; < 0.65.1 (affected, semver); OSV events: introduced 0.55.0; fixed 0.65.1Source events (semver)Other versions: unaffected |
OSV GHSA-9264-jvgf-6w2f |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 3.1 / 3.7 low |
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N | CNA: GitHub_M |
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://github.com/Eugeny/russh/security/advisories/GHSA-9264-jvgf-6w2fCNA: GitHub_M · x_refsource_CONFIRM
- https://github.com/Eugeny/russh/pull/808CNA: GitHub_M · x_refsource_MISC
- https://github.com/Eugeny/russh/commit/43a46d67a80a7355fcd2fb25e7e00d79aec8184cCNA: GitHub_M · x_refsource_MISC
- https://github.com/Eugeny/russh/releases/tag/v0.65.1CNA: GitHub_M · x_refsource_MISC
- https://github.com/advisories/GHSA-9264-jvgf-6w2fOSV / GitHub Security Advisories · advisory
- https://osv.dev/vulnerability/GHSA-9264-jvgf-6w2fOSV / GitHub Security Advisories · osv
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