Russh: Unbounded memory exhaustion via CHANNEL_OPEN flood during a client-stalled rekey
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.
CVE-2026-102821
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-102821
russh
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"vendor": "Eugeny",
"product": "russh",
"versions": [
{
"status": "affected",
"version": "< 0.63.2"
}
]
}
]- Related CVEs
- CVE-2026-102821
Source reference:
/cveMetadata/cveId
Publisher severity
medium
Source reference: /containers/cna/metrics
- Event
- #4843 · Revision 1
- Added to Heist Feed
- Publisher date