CVE-2026-73430

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.

CVSS v3 5.3 MEDIUM

5.3^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 3.9 / Impact : 1.4

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact LOW

Scope UNCHANGED

References

Link	Resource
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-5xvq-cp9x-6p6r

Configurations

No configuration.

History

23 Oct 2026, 19:10

Type	Values Removed	Values Added
Summary		(es) Russh es una biblioteca SSH de cliente y servidor de Rust. Antes de la versión 0.62.4, un cliente SSH no autenticado puede causar una denegación de servicio al enviar SSH_MSG_KEX_ECDH_INIT con un valor Q_C de 32 bytes todo ceros. Curve25519Kex::server_dh en russh/src/kex/curve25519.rs acepta el valor público del par todo ceros y calcula un secreto compartido todo ceros, después de lo cual compute_exchange_hash llama a encode_mpint en russh/src/kex/mod.rs e indexa más allá del final de la entrada mientras omite los bytes cero iniciales. El pánico resultante ocurre antes de la autenticación y termina la tarea de intercambio de claves del servidor. Este problema está solucionado en la versión 0.62.4.

Information

Published : 2026-08-12 21:17

Updated : 2026-10-24 15:10

NVD link : CVE-2026-73430

Mitre link : CVE-2026-73430

CVE.ORG link : CVE-2026-73430

JSON object : View

Products Affected

No product.

CWE

CWE-754

Improper Check for Unusual or Exceptional Conditions

{"id": "CVE-2026-73430", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-73430", "role": "CISA Coordinator", "options": [{"exploitation": "none"}, {"automatable": "yes"}, {"technicalImpact": "partial"}], "version": "2.0.3", "timestamp": "2026-08-13T17:49:19.811444Z"}}], "cvssMetricV31": [{"type": "Secondary", "source": "security-advisories@github.com", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 5.3, "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "LOW", "privilegesRequired": "NONE", "confidentialityImpact": "NONE"}, "impactScore": 1.4, "exploitabilityScore": 3.9}]}, "affected": [{"source": "security-advisories@github.com", "affectedData": [{"vendor": "Eugeny", "product": "russh", "versions": [{"status": "affected", "version": "< 0.62.4"}]}]}], "published": "2026-08-12T21:17:41.883", "references": [{"url": "https://github.com/Eugeny/russh/commit/a7fc1eb5717264e31c3c5f7dd849b73989a08f3d", "source": "security-advisories@github.com"}, {"url": "https://github.com/Eugeny/russh/releases/tag/v0.62.4", "source": "security-advisories@github.com"}, {"url": "https://github.com/Eugeny/russh/security/advisories/GHSA-5xvq-cp9x-6p6r", "source": "security-advisories@github.com"}], "vulnStatus": "Deferred", "weaknesses": [{"type": "Secondary", "source": "security-advisories@github.com", "description": [{"lang": "en", "value": "CWE-754"}]}], "descriptions": [{"lang": "en", "value": "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."}, {"lang": "es", "value": "Russh es una biblioteca SSH de cliente y servidor de Rust. Antes de la versi\u00f3n 0.62.4, un cliente SSH no autenticado puede causar una denegaci\u00f3n de servicio al enviar SSH_MSG_KEX_ECDH_INIT con un valor Q_C de 32 bytes todo ceros. Curve25519Kex::server_dh en russh/src/kex/curve25519.rs acepta el valor p\u00fablico del par todo ceros y calcula un secreto compartido todo ceros, despu\u00e9s de lo cual compute_exchange_hash llama a encode_mpint en russh/src/kex/mod.rs e indexa m\u00e1s all\u00e1 del final de la entrada mientras omite los bytes cero iniciales. El p\u00e1nico resultante ocurre antes de la autenticaci\u00f3n y termina la tarea de intercambio de claves del servidor. Este problema est\u00e1 solucionado en la versi\u00f3n 0.62.4."}], "lastModified": "2026-10-24T15:10:00.190", "sourceIdentifier": "security-advisories@github.com"}