What’s Vulnerable › Vulnerabilities

CVE-2026-73429: Russh: client wrong-length X25519 `clone_from_slice` panic (pre-auth DoS)

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-12 · updated 2026-10-24
• Weakness: CWE-704

Description

Russh is a Rust SSH client & server library. Prior to 0.62.4, a malicious SSH server can crash a russh client session with a malformed KEX_ECDH_REPLY containing a server ephemeral value that is not 32 bytes long. The client-side Curve25519Kex::compute_shared_secret function in russh/src/kex/curve25519.rs passes the decoded exchange.server_ephemeral value to clone_from_slice without validating its length, causing a deterministic panic before the server host key is verified. The panic terminates the spawned client session task and surfaces as a JoinError, while the embedding process normally remains running. This issue is fixed in version 0.62.4.

Affected products

• Eugeny russh: before 0.62.4

References

• https://github.com/Eugeny/russh/commit/a7fc1eb5717264e31c3c5f7dd849b73989a08f3d
• https://github.com/Eugeny/russh/releases/tag/v0.62.4
• https://github.com/Eugeny/russh/security/advisories/GHSA-g9hv-x236-4qp3
• https://github.com/Eugeny/russh/security/advisories/GHSA-g9hv-x236-4qp3

Get alerted when CVE-2026-73429 or the next vulnerability affects your stack