CVE-2026-73429

MEDIUMCVSS 5.3/10EPSS 0.29%

Last modified

CVE-2026-73429 is a medium-severity vulnerability rated 5.3/10 on the CVSS scale. 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. EPSS estimates a 0.29% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
5.3/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS Probability
0.29%

21.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
Eugenyrussh< 0.62.4

References

Timeline

Published
Last Modified
Status
Received

Frequently Asked Questions

What is CVE-2026-73429?
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.
How severe is CVE-2026-73429?
CVE-2026-73429 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 0.29% probability of exploitation in the next 30 days.
How do I fix CVE-2026-73429?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST