---
id: CVE-2019-16905
title: >-
  OpenSSH 7.7 through 7.9 and 8.x before 8.1, when compiled with an experimental
  key type, has a pre-authentication integer overflow if a client or server is
  configured to use a crafted XMSS key
summary: >-
  OpenSSH 7.7 through 7.9 and 8.x before 8.1, when compiled with an experimental
  key type, has a pre-authentication integer overflow if a client or server is
  configured to use a crafted XMSS key. This leads to memory corruption and
  local c…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-190
vendor: openbsd
product: openssh
affected:
  - 'openssh >= 7.7, <= 7.9'
  - 'openssh >= 8.0, < 8.1'
  - cloud_backup
  - steelstore_cloud_integrated_storage
  - scalance_x204rna_firmware < 3.2.7
  - scalance_x204rna_ecc_firmware < 3.2.7
patched:
  - openssh 8.1
  - scalance_x204rna_firmware 3.2.7
  - scalance_x204rna_ecc_firmware 3.2.7
published: '2019-10-09'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T07:16:48.583'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2019-16905'
references:
  - url: 'https://bugzilla.suse.com/show_bug.cgi?id=1153537'
    label: cve@mitre.org
  - url: 'https://cert-portal.siemens.com/productcert/pdf/ssa-412672.pdf'
    label: cve@mitre.org
  - url: 'https://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/sshkey-xmss.c'
    label: cve@mitre.org
  - url: >-
      https://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/sshkey-xmss.c.diff?r1=1.5&r2=1.6&f=h
    label: cve@mitre.org
  - url: 'https://security.gentoo.org/glsa/201911-01'
    label: cve@mitre.org
  - url: 'https://security.netapp.com/advisory/ntap-20191024-0003/'
    label: cve@mitre.org
  - url: >-
      https://ssd-disclosure.com/archives/4033/ssd-advisory-openssh-pre-auth-xmss-integer-overflow
    label: cve@mitre.org
  - url: 'https://www.openssh.com/releasenotes.html'
    label: cve@mitre.org
  - url: 'https://www.openwall.com/lists/oss-security/2019/10/09/1'
    label: cve@mitre.org
  - url: 'https://bugzilla.suse.com/show_bug.cgi?id=1153537'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://cert-portal.siemens.com/productcert/pdf/ssa-412672.pdf'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/sshkey-xmss.c'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/sshkey-xmss.c.diff?r1=1.5&r2=1.6&f=h
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://security.gentoo.org/glsa/201911-01'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://security.netapp.com/advisory/ntap-20191024-0003/'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://ssd-disclosure.com/archives/4033/ssd-advisory-openssh-pre-auth-xmss-integer-overflow
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://www.openssh.com/releasenotes.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://www.openwall.com/lists/oss-security/2019/10/09/1'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-398330.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-412672.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
epss: 0.0217
epssPercentile: 0.81813
ingestedAt: '2026-10-14T07:21:04.820Z'
---

## Overview

OpenSSH 7.7 through 7.9 and 8.x before 8.1, when compiled with an experimental key type, has a pre-authentication integer overflow if a client or server is configured to use a crafted XMSS key. This leads to memory corruption and local code execution because of an error in the XMSS key parsing algorithm. NOTE: the XMSS implementation is considered experimental in all released OpenSSH versions, and there is no supported way to enable it when building portable OpenSSH.

## Affected

- `openssh >= 7.7, <= 7.9`
- `openssh >= 8.0, < 8.1`
- `cloud_backup`
- `steelstore_cloud_integrated_storage`
- `scalance_x204rna_firmware < 3.2.7`
- `scalance_x204rna_ecc_firmware < 3.2.7`

## Remediation

Upgrade past the affected range:

- `openssh 8.1`
- `scalance_x204rna_firmware 3.2.7`
- `scalance_x204rna_ecc_firmware 3.2.7`