CVE-2026-111061 Details
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.
A memory exhaustion vulnerability has been identified in the russh SSH client and server library, prior to version 0.64.1. The issue arises in the agent protocol implementation, where the agent server improperly handles constrained add-key requests. Specifically, for each SSH_AGENT_CONSTRAIN_LIFETIME record, a separate long-lived task is spawned that clones the key blob and sleeps for the specified duration. This unbounded task creation continues until the agent process is starved or terminated, leading to a denial of service. The vulnerability can be exploited by an attacker who can communicate with the agent protocol locally or through agent forwarding.
Users can upgrade to russh version 0.64.1 or later, where this vulnerability has been fixed.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Oct 19, 2026CISA-ADP
Assessed Oct 19, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/Eugeny/russh/security/advisories/GHSA-4wc5-f2rc-q74m | CISA-ADP | AdvisoryExploitRemedyVendor |
| https://github.com/Eugeny/russh/commit/4c305033d72f8e5dd21a3fd4c53a6c291a16ebd1 | [email protected] | Source CodeVendor |
| https://github.com/Eugeny/russh/releases/tag/v0.64.1 | [email protected] | Release NotesVendor |
| https://github.com/Eugeny/russh/security/advisories/GHSA-4wc5-f2rc-q74m | [email protected] | AdvisoryExploitRemedyVendor |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-770 | Allocation of Resources Without Limits or Throttling | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| Eugeny russh | <= 0.64.0 (semver) |
CPE
Remediation
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Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Oct 19, 2026 | CVE Modified | CISA-ADP |
| Oct 19, 2026 | New CVE Received | [email protected] |