# CVE-2026-73430

## Summary

- **CVE ID:** CVE-2026-73430
- **Severity:** MEDIUM
- **CVSS Score:** 5.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L)
- **CWE:** CWE-754
- **Published:** Aug 12, 2026
- **Last Modified:** Aug 13, 2026

## Description

Russh is a Rust SSH client & server library. Prior to 0.62.4, an unauthenticated SSH client can cause a denial of service by sending SSH_MSG_KEX_ECDH_INIT with a 32-byte all-zero Q_C value. Curve25519Kex::server_dh in russh/src/kex/curve25519.rs accepts the all-zero peer public value and computes an all-zero shared secret, after which compute_exchange_hash calls encode_mpint in russh/src/kex/mod.rs and indexes beyond the end of the input while skipping leading zero bytes. The resulting panic occurs before authentication and terminates the server key-exchange task. This issue is fixed in version 0.62.4.

## Affected Products

- Eugeny — russh (< 0.62.4)

## References

- [CNA](https://github.com/Eugeny/russh/security/advisories/GHSA-5xvq-cp9x-6p6r)
- [CNA](https://github.com/Eugeny/russh/commit/a7fc1eb5717264e31c3c5f7dd849b73989a08f3d)
- [CNA](https://github.com/Eugeny/russh/releases/tag/v0.62.4)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.33%
- **EPSS Percentile:** 26.1

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-11._