CVE-2026-126641 (GCVE-0-2026-126641)
Vulnerability from cvelistv5 – Published: 2026-11-12 10:47 – Updated: 2026-11-13 00:13
VLAI
EPSS
VEX
Title
Ansible-pylibssh: accepts a changed ssh host key when host_key_auto_add is enabled
Summary
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.
Severity
6.5 (Medium)
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-11-13 00:13 UTC
CWE
- CWE-322 - Key Exchange without Entity Authentication
Assigner
redhat
CNA
References
3 references
| URL | Tags |
|---|---|
| https://access.redhat.com/security/cve/CVE-2026-126641 | vdb-entryx_refsource_REDHAT |
| https://bugzilla.redhat.com/show_bug.cgi?id=2571719 | issue-trackingx_refsource_REDHAT |
| http://www.openwall.com/lists/oss-security/2026/11/12/6 |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Red Hat | Red Hat Ansible Automation Platform 2 |
cpe:/a:redhat:ansible_automation_platform:2
|
Date Public
2026-11-11 14:19
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