Russh: Unbounded memory exhaustion via CHANNEL_OPEN flood during a client-stalled rekey — GHSA-35G8-35P8-C8FW

Summary

## Summary A russh **server** can be driven to unbounded heap growth (process OOM / kill) by a peer that speaks only standard SSH messages, in the **default configuration**. The peer starts a key re-exchange (sends `SSH_MSG_KEXINIT`) but never sends the follow-up `SSH_MSG_KEX_ECDH_INIT`, leaving the server's kex state machine in `SessionKexState::InProgress` **indefinitely**. While a rekey is in progress the…

Timeline

Published by source

2026-09-30

Risk context

• Reported severity or threat level: medium.
• Reported CVSS score: 6.5 out of 10.
• Reported EPSS value: 0.00295.
• Review exposure for the affected product or family: rust: russh.

Product

rust: russh

What to do

General, cautious steps (verify details in the official source):

• Review exposure and plan remediation based on risk and environment.
• Identify affected product versions in your inventory and verify whether you are impacted.
• Apply vendor patches/updates or recommended mitigations as soon as available.
• Read the official advisory for exact affected versions and remediation steps.

Official advisory

• Read the official source
• CVE Record
• NVD

Evidence and provenance

Canonical advisory ID

GHSA-35G8-35P8-C8FW

Source

GitHub

Vendor

GitHub

Published by source

2026-09-30

Last source activity

2026-09-30

Additional identifiers

CVE-2026-102821

Curated by

hlukh.ch

Related advisories and connections

These advisories are connected by shared CVE, product, vendor, source, or time signals.