Read the docs
TI-2026-76432 Aliases CVE-2026-111061GHSA-4wc5-f2rc-q74m

Unbounded task creation in russh SSH agent server exhausts memory

Priority MEDIUM 53CWE-770Published · Updated

Key facts

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

Attack profile from CVSS 3.1 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-770.

Summary

Eugeny russh, a Rust SSH client and server library, is affected before 0.64.1. Its SSH agent server creates a separate long-lived task for each lifetime constraint record in an add-key request and does not roll back those tasks when later constraint parsing fails (CWE-770). An attacker who 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.

Written with Claude Haiku 5.5 from the sources below · 2026-11-03

Description from the CNA

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00347 28th percentileScored 2026-11-07
Fix Fixed russh (Eugeny): 0.64.1russh (crates.io): 0.64.1Red Hat: 2 advisories

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 0.64.10.64.1Patch availableCNA
—russh (crates.io)before 0.64.10.64.1Patch availableGHSA-4wc5-f2rc-q74m
  • russh VendorEugeny Affected before 0.64.1 Fixed in 0.64.1 Patch available CNA
  • russh (crates.io) Vendor— Affected before 0.64.1 Fixed in 0.64.1 Patch available GHSA-4wc5-f2rc-q74m

Remediation

Upgrade russh to version 0.64.1, the fixed version for both the Eugeny russh and crates.io entries. Red Hat Hardened Images is fixed by RHSA-2026:93904 and RHSA-2026:90366.

Written with Claude Haiku 5.5 from the sources below · 2026-11-03

  • Fix · CNA russh (Eugeny) Fixed in 0.64.1
  • Fix · GHSA-4wc5-f2rc-q74m russh (crates.io) Fixed in 0.64.1 Advisory →

Red Hat 2 advisories

  • RHSA-2026:93904 Released 2026-11-02 · Red Hat rating Moderate
    Red Hat Hardened Images RPMs Security Update
    • Red Hat Hardened Images openshell-0.1.6-0.1.hum1@aarch64, openshell-0.1.6-0.1.hum1@src, openshell-0.1.6-0.1.hum1@x86_64 +4
  • RHSA-2026:90366 Released 2026-10-26 · Red Hat rating Moderate
    Red Hat Hardened Images RPMs bug fix and enhancement update
    • Red Hat Hardened Images openshell-0.1.5-0.1.hum1@aarch64, openshell-0.1.5-0.1.hum1@src, openshell-0.1.5-0.1.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-2026:90366, RHSA-2026:93904

Timeline

  1. 2026-10-19 Threatist record created from CVE-2026-111061
  2. 2026-10-20 CISA SSVC decision points changed
  3. 2026-10-20 Priority changed: LOW → MEDIUM
  4. 2026-10-20 Alias added: GHSA-4wc5-f2rc-q74m
  5. 2026-10-20 Fix available: crates.io/[email protected] · GHSA-4wc5-f2rc-q74m
  6. 2026-10-20 CVSS score added · GHSA-4wc5-f2rc-q74m
  7. 2026-10-20 Weakness changed · GHSA-4wc5-f2rc-q74m
  8. 2026-10-20 4 new references · GHSA-4wc5-f2rc-q74m
  9. 2026-10-20 Affected versions changed · Red Hat
  10. 2026-10-20 CVSS score added · Red Hat
  11. 2026-10-30 Fix available: RHSA-2026:90366 · Red Hat
  12. 2026-10-30 Fix available: Red Hat Hardened Images · Red Hat
  13. 2026-11-03 Fix available: RHSA-2026:93904 · Red Hat
  14. 2026-11-03 Affected versions changed · Red Hat

References

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