Description
russh is a Rust SSH client and server library that includes an SSH agent protocol implementation. Prior to 0.64.1, the agent server spawns a separate long-lived task for every SSH_AGENT_CONSTRAIN_LIFETIME record in a constrained add-key request. The loop accepts repeated lifetime records, clones the key blob into each task, and does not roll back tasks when later constraint parsing fails. An attacker that can speak the agent protocol locally or through agent forwarding can exhaust memory and tasks until the agent process is starved or terminated, denying SSH agent service. This issue is fixed in version 0.64.1.
Published: 2026-10-19
Score: 4.3 Medium
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-4wc5-f2rc-q74m russh: Unbounded memory allocation in agent protocol server via crafted constraint records
History

Mon, 19 Oct 2026 19:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Mon, 19 Oct 2026 16:45:00 +0000

Type Values Removed Values Added
Description russh is a Rust SSH client and server library that includes an SSH agent protocol implementation. Prior to 0.64.1, the agent server spawns a separate long-lived task for every SSH_AGENT_CONSTRAIN_LIFETIME record in a constrained add-key request. The loop accepts repeated lifetime records, clones the key blob into each task, and does not roll back tasks when later constraint parsing fails. An attacker that can speak the agent protocol locally or through agent forwarding can exhaust memory and tasks until the agent process is starved or terminated, denying SSH agent service. This issue is fixed in version 0.64.1.
Title russh agent server converts constraint records into unbounded never-rolled-back tasks
Weaknesses CWE-770
References
Metrics cvssV3_1

{'score': 4.3, 'vector': 'CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'}

Subscriptions

No data.

cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-10-19T18:29:47.486Z

Reserved: 2026-10-15T12:47:13.665Z

Link: CVE-2026-111061

cve-icon Vulnrichment

Updated: 2026-10-19T18:29:41.958Z

cve-icon NVD

Status : Deferred

Published: 2026-10-19T17:17:03.080

Modified: 2026-10-19T19:17:22.890

Link: CVE-2026-111061

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-19T18:00:02Z

Weaknesses
  • CWE-770

    Allocation of Resources Without Limits or Throttling