Medium severity · published Aug 12, 2026
CVE-2026-73429
Russh: client wrong-length X25519 `clone_from_slice` panic (pre-auth DoS)
5.3
CVSS
0.5%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
Low
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 43% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
RU
russh · Eugeny
< 0.62.4 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-73429
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-73429
github.com
https://github.com/Eugeny/russh/commit/a7fc1eb5717264e31c3c5f7dd849b73989a08f3d
github.com
https://github.com/Eugeny/russh/releases/tag/v0.62.4
github.com
https://github.com/Eugeny/russh/security/advisories/GHSA-g9hv-x236-4qp3
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