Russh is a Rust SSH client and server library. Prior to 0.63.2, an authenticated remote peer can send SSH_MSG_KEXINIT without the required SSH_MSG_KEX_ECDH_INIT and then flood SSH_MSG_CHANNEL_OPEN messages while SessionKexState::InProgress prevents priority_receiver in russh/src/server/session.rs from being drained. The server continues processing network input and enqueues a ChannelOpenReply for each request on an unbounded channel, allowing one connection to grow memory until the process is terminated. This issue is fixed in version 0.63.2.
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Tue, 29 Sep 2026 18:30:00 +0000

Type Values Removed Values Added
Description Russh is a Rust SSH client and server library. Prior to 0.63.2, an authenticated remote peer can send SSH_MSG_KEXINIT without the required SSH_MSG_KEX_ECDH_INIT and then flood SSH_MSG_CHANNEL_OPEN messages while SessionKexState::InProgress prevents priority_receiver in russh/src/server/session.rs from being drained. The server continues processing network input and enqueues a ChannelOpenReply for each request on an unbounded channel, allowing one connection to grow memory until the process is terminated. This issue is fixed in version 0.63.2.
Title Russh: Unbounded memory exhaustion via CHANNEL_OPEN flood during a client-stalled rekey
Weaknesses CWE-400
CWE-770
References
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-09-29T18:21:21.858Z

Reserved: 2026-09-29T17:25:25.265Z

Link: CVE-2026-102821

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Deferred

Published: 2026-09-29T19:17:23.993

Modified: 2026-09-29T19:17:24.140

Link: CVE-2026-102821

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses