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CVE-2026-126641

Ansible-pylibssh: accepts a changed ssh host key when host_key_auto_add is enabled

Products / packages Red Hat Ansible Automation Platform 2

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Severity and exploitation

Not in CISA KEV

KEV coverage does not rule out exploitation.

KEV checked 15/11/2026, 00:35:33 UTC
redhat · CVSS:3.1 · 6.5
Assessment vectorCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N

Severity

medium6.5

CVSS measures technical severity, not the likelihood of an attack.

Known exploitation

Not listed in the checked CISA KEV catalog

Absence from CISA KEV does not rule out attacks.

Public exploit

Not established by this record

Missing evidence does not mean no public exploit exists.

Remediation

Source guidance available

Review the recorded instructions. Guidance may be a workaround rather than a fixed version.

What this means

Ansible-pylibssh and the ansible.netcommon libssh connection plugin have a host key verification flaw when trust-on-first-use is enabled, allowing a host with a changed key to be accepted without warning. This can disclose connection credentials to an attacker. Default configurations are not affected.

Summarized by @cf/meta/llama-3.3-70b-instruct-fp8-fast. Verify details against the original sources.

Attack conditions

No attack-condition excerpt has been identified here. Review the full source description and references for authentication, network access, and configuration requirements.

Review supporting sources →

Affected versions

Check the exact model, release, and any platform requirements against your installation.

Red Hat · redhat

Red Hat Ansible Automation Platform 2

0 ranges
redhat version evidence

Compare with this publisher’s ranges. This does not inspect your installation.

affected

unaffected

unknown

Other versions: affected

Product identifiers (CPE)cpe:/a:redhat:ansible_automation_platform:2

Red Hat · redhat

Red Hat Ansible Automation Platform 2

0 ranges
redhat version evidence

Compare with this publisher’s ranges. This does not inspect your installation.

affected

unaffected

unknown

Other versions: affected

Product identifiers (CPE)cpe:/a:redhat:ansible_automation_platform:2

Red Hat · redhat

Red Hat Ansible Automation Platform 2

0 ranges
redhat version evidence

Compare with this publisher’s ranges. This does not inspect your installation.

affected

unaffected

unknown

Other versions: affected

Product identifiers (CPE)cpe:/a:redhat:ansible_automation_platform:2

Red Hat · redhat

Red Hat Ansible Automation Platform 2

0 ranges
redhat version evidence

Compare with this publisher’s ranges. This does not inspect your installation.

affected

unaffected

unknown

Other versions: affected

Product identifiers (CPE)cpe:/a:redhat:ansible_automation_platform:2

Red Hat · redhat

Red Hat Ansible Automation Platform 2

0 ranges
redhat version evidence

Compare with this publisher’s ranges. This does not inspect your installation.

affected

unaffected

unknown

Other versions: affected

Product identifiers (CPE)cpe:/a:redhat:ansible_automation_platform:2

Red Hat · redhat

Red Hat Ansible Automation Platform 2

0 ranges
redhat version evidence

Compare with this publisher’s ranges. This does not inspect your installation.

affected

unaffected

unknown

Other versions: affected

Product identifiers (CPE)cpe:/a:redhat:ansible_automation_platform:2
Automatic dependency matching is unavailable for this record. Use the product evidence and publisher’s instructions to check your installation.

What to do

Compare your installed product and version with the affected versions above. A matching product name alone does not confirm exposure.

Do not enable host_key_auto_add (ansible.netcommon libssh) or AutoAddPolicy (ansible-pylibssh). Keep host_key_checking enabled and pre-populate known_hosts with verified host keys so that a changed key causes the connection to fail closed.

redhat guidance ↗

cve.new guidance unless attributed to a publisher. This page does not inspect your installation.

Public exploit evidence

No public exploit reference is identified in the imported evidence. This is not a claim that no exploit exists.

Original source description

Read the full publisher description

A host key verification flaw was found in ansible-pylibssh and in the ansible.netcommon libssh connection plugin. When trust-on-first-use is enabled (host_key_auto_add on the libssh connection plugin, or AutoAddPolicy in ansible-pylibssh), a host that is already present in known_hosts but now presents a different key is accepted without warning. The pylibssh Session.verify_knownhost() method passes the SSH_KNOWN_HOSTS_CHANGED and SSH_KNOWN_HOSTS_OTHER states to the same missing_host_key() policy hook used for unknown hosts, and the bundled AutoAddPolicy/RejectPolicy classes (as well as ansible.netcommon's MyAddPolicy, which is modeled on paramiko's AutoAddPolicy) therefore add the changed key and continue the connection rather than aborting as paramiko's BadHostKeyException path would. As a result the controller authenticates to the substitute host, runs the play there, and appends the new key to known_hosts, which can disclose connection credentials to an attacker performing a machine-in-the-middle attack. Default configurations (host_key_checking enabled, host_key_auto_add unset) are not affected; non-interactive runs fail closed.

References

3 sources
access.redhat.com/security/cve/CVE-2026-126641
Security advisoryredhat
bugzilla.redhat.com/show_bug.cgi
Source referenceredhat
www.openwall.com/lists/oss-security/2026/11/12/6
Security advisoryCVE

Inside the record

Evidence available

Package identity · not supplied
Version evidence · not supplied
Remediation guidance
Weakness classification
Additional publishers

Describes the evidence in this view, not whether the product is safe.

Original records

CVE-2026-126641

View the latest unmodified CVE JSON from the official source. It may be newer than this imported page.

cve.new JSON →

Underlying weaknesses

The source’s classification of what caused the vulnerability.

CWE-322 ↗

Key Exchange without Entity Authentication

redhat

Related →
Contributing organizations · 3
redhat

Assigning organization

2026-11-12
CVE

Additional data publisher

2026-11-12
CISA-ADP

Additional data publisher

2026-11-13

Timeline

All times UTC

  1. Advisory published

    Publication date supplied by the source.

  2. Source updated

    Latest modification date supplied by the source.

  3. Last imported by cve.new

    Latest catalog import, not the date we first saw this advisory.

What changed

Follow changes
  1. CVE · CVE-2026-126641

    Observed 2026-11-13T00:54:24.537Z · upstream updated 2026-11-13T00:13:47.383Z

    Prioritization updated

    before

    []

    after

    [
  {
    "source": "CISA-ADP",
    "type": "SSVC",
    "role": "CISA Coordinator",
    "timestamp": "2026-11-13T00:13:37.625389Z",
    "decisions": [
      {
        "name": "Exploitation",
        "value": "none"
      },
      {
        "name": "Automatable",
        "value": "no"
      },
      {
        "name": "Technical Impact",
        "value": "partial"
      }
    ]
  }
]
  2. CVE · CVE-2026-126641

    Observed 2026-11-12T22:37:11.775Z · upstream updated 2026-11-12T22:04:12.796Z

    References changed

    before

    [
  "https://access.redhat.com/security/cve/CVE-2026-126641",
  "https://bugzilla.redhat.com/show_bug.cgi?id=2571719"
]

    after

    [
  "https://access.redhat.com/security/cve/CVE-2026-126641",
  "https://bugzilla.redhat.com/show_bug.cgi?id=2571719",
  "http://www.openwall.com/lists/oss-security/2026/11/12/6"
]

Large field values are marked as truncated previews. Original source snapshots remain retained.

Showing up to 50 most recent observed changes.