---
id: CVE-2021-28041
title: >-
  ssh-agent in OpenSSH before 8.5 has a double free that may be relevant in a
  few less-common scenarios, such as unconstrained agent-socket access on a
  legacy operating system, or the forwarding of an agent to an
  attacker-controlled host.
summary: >-
  ssh-agent in OpenSSH before 8.5 has a double free that may be relevant in a
  few less-common scenarios, such as unconstrained agent-socket access on a
  legacy operating system, or the forwarding of an agent to an
  attacker-controlled host.
severity: high
cvss: 7.1
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H'
cwe:
  - CWE-415
vendor: openbsd
product: openssh
affected:
  - 'openssh >= 8.2, < 8.5'
  - fedora = 33
  - fedora = 34
  - cloud_backup
  - hci_management_node
  - solidfire
  - hci_compute_node_firmware
  - hci_storage_node_firmware
  - communications_offline_mediation_controller = 12.0.0.3.0
  - zfs_storage_appliance = 8.8
patched:
  - openssh 8.5
published: '2021-03-05'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T12:17:10.697'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2021-28041'
references:
  - url: >-
      https://github.com/openssh/openssh-portable/commit/e04fd6dde16de1cdc5a4d9946397ff60d96568db
    label: cve@mitre.org
  - url: >-
      https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/KQWGII3LQR4AOTPPFXGMTYE7UDEWIUKI/
    label: cve@mitre.org
  - url: >-
      https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TXST2CML2MWY3PNVUXX7FFJE3ATJMNVZ/
    label: cve@mitre.org
  - url: 'https://security.gentoo.org/glsa/202105-35'
    label: cve@mitre.org
  - url: 'https://security.netapp.com/advisory/ntap-20210416-0002/'
    label: cve@mitre.org
  - url: 'https://www.openssh.com/security.html'
    label: cve@mitre.org
  - url: 'https://www.openssh.com/txt/release-8.5'
    label: cve@mitre.org
  - url: 'https://www.openwall.com/lists/oss-security/2021/03/03/1'
    label: cve@mitre.org
  - url: 'https://www.oracle.com//security-alerts/cpujul2021.html'
    label: cve@mitre.org
  - url: >-
      https://github.com/openssh/openssh-portable/commit/e04fd6dde16de1cdc5a4d9946397ff60d96568db
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/KQWGII3LQR4AOTPPFXGMTYE7UDEWIUKI/
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TXST2CML2MWY3PNVUXX7FFJE3ATJMNVZ/
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://security.gentoo.org/glsa/202105-35'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://security.netapp.com/advisory/ntap-20210416-0002/'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://www.openssh.com/security.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://www.openssh.com/txt/release-8.5'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://www.openwall.com/lists/oss-security/2021/03/03/1'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://www.oracle.com//security-alerts/cpujul2021.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-398330.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
  - cve.org
epss: 0.03422
epssPercentile: 0.88634
ingestedAt: '2026-10-14T12:29:10.816Z'
---

## Overview

ssh-agent in OpenSSH before 8.5 has a double free that may be relevant in a few less-common scenarios, such as unconstrained agent-socket access on a legacy operating system, or the forwarding of an agent to an attacker-controlled host.

## Affected

- `openssh >= 8.2, < 8.5`
- `fedora = 33`
- `fedora = 34`
- `cloud_backup`
- `hci_management_node`
- `solidfire`
- `hci_compute_node_firmware`
- `hci_storage_node_firmware`
- `communications_offline_mediation_controller = 12.0.0.3.0`
- `zfs_storage_appliance = 8.8`

## Remediation

Upgrade past the affected range:

- `openssh 8.5`