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TI-2026-65510 Aliases CVE-2026-102821GHSA-35g8-35p8-c8fw

Russh: Unbounded memory exhaustion via CHANNEL_OPEN flood during a client-stalled rekey

Priority MEDIUM 62CWE-400Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-400.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00358 29th percentileScored 2026-11-07
Fix Fixed russh (Eugeny): 0.63.2russh (crates.io): 0.63.2Red Hat: 1 advisory

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
Eugenyrusshbefore 0.63.20.63.2Patch availableCNA
—russh (crates.io)before 0.63.20.63.2Patch availableGHSA-35g8-35p8-c8fw
  • russh VendorEugeny Affected before 0.63.2 Fixed in 0.63.2 Patch available CNA
  • russh (crates.io) Vendor— Affected before 0.63.2 Fixed in 0.63.2 Patch available GHSA-35g8-35p8-c8fw

Remediation

  • Fix · CNA russh (Eugeny) Fixed in 0.63.2
  • Fix · GHSA-35g8-35p8-c8fw russh (crates.io) Fixed in 0.63.2 Advisory →

Red Hat 1 advisory

  • RHSA-2026:74586 Released 2026-10-01 · Red Hat rating Important
    Red Hat Hardened Images RPMs Security Update
    • Red Hat Hardened Images openshell-0.1.2-0.2.hum1@aarch64, openshell-0.1.2-0.2.hum1@src, openshell-0.1.2-0.2.hum1@x86_64 +4

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Hardened ImagesFixed RHSA-2026:74586

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-102821
  2. 2026-10-03 Alias added: GHSA-35g8-35p8-c8fw

References

Advisory 1

Other 4

  • TI-2026-65512 russh: Client-side channel-scoped Handler callbacks fire for channel IDs the client never opened CVSS 3.1HIGH 7.5
  • TI-2026-35550 Russh: SSH message fields were decoded through allocation-first parsers before field-specific bounds CVSS 3.1HIGH 7.5
  • TI-2026-34331 Russh: Post-decompression SSH packet size was not bounded, allowing remote oversized compressed packets CVSS 3.1HIGH 7.5
  • TI-2026-34308 Resource allocation without limits in Eugeny russh CVSS 3.1HIGH 7.5
  • TI-2025-16084 Tabby has a TCC Bypass via Misconfigured Node Fuses CVSS 4.0HIGH 8.6
  • TI-2024-36991 Tabby has a TCC Bypass via Unnecessary Permissive Entitlements in Tabby CVSS 4.0HIGH 8.6
See all 25 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences