CVE-2026-42189Network attack vector

Pre-authentication crash via unbounded response allocation

Published May 8, 2026 · Updated May 8, 2026

Resource exhaustion in Eugeny russh before 0.60.1 allows remote attackers to crash affected SSH servers with a malformed authentication packet. In read_userauth_info_response, a client-supplied u32 response count is passed directly to Vec::with_capacity, permitting a multi-gigabyte allocation. Only servers whose keyboard-interactive handler returns Auth::Partial are affected; the default handler rejects this flow, and exploitation kills the process and all active sessions.

CVSS severity7.5
High
EPSS probability0.48%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in Eugeny russh before 0.60.1 allows remote attackers to crash affected SSH servers with a malformed authentication packet. In read_userauth_info_response, a client-supplied u32 response count is passed directly to Vec::with_capacity, permitting a multi-gigabyte allocation. Only servers whose keyboard-interactive handler returns Auth::Partial are affected; the default handler rejects this flow, and exploitation kills the process and all active sessions.

The record

CVE
CVE-2026-42189
Published
May 8, 2026
Updated
May 8, 2026
Vendor
Russh Project
Product
russh
Classifications
CWE-770, CWE-789, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 8, 2026CVE publishedPublication date reported by the CVE source.
  2. May 8, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 0.60.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Russh Project · russhversion=< 0.60.1

Published CVSS scores

7.5GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
CWE-789Memory Allocation with Excessive Size Value
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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