CPANSA-Rex-2026-94140: Rex vulnerability
| Publisher | giterlizzi | Document category | csaf_security_advisory |
|---|---|---|---|
| Initial release date | 2026-10-21T00:00:00 | Engine | CSAF Perl Toolkit 0.26 |
| Current release date | 2026-10-21T00:00:00 | Build Date | |
| Current version | 1 | Status | final |
| CVSS v3.1 Base Score | Severity | ||
| Original language | Language | en | |
| Also referred to | |||
Vulnerability Description
Rex versions through 1.16.1 for Perl accept an unknown SSH host key for remote rsync transfers because sync hardcodes StrictHostKeyChecking=no.
Every remote branch of sync builds its ssh command with that option, for password authentication, for private-key authentication and for the fallback. The ssh options a caller sets through set_openssh_opt reach the OpenSSH transport but not this command, so there is no configuration that restores host key checking for the transfer.
An attacker who can redirect the connection before the real host key is known presents their own and the transfer proceeds: under password authentication sync sends the connection password to that server, an upload writes the selected local files to it, and a download writes what it returns to the local destination.
Vulnerabilities
CVE-2026-94140
Vulnerability DescriptionRex versions through 1.16.1 for Perl accept an unknown SSH host key for remote rsync transfers because sync hardcodes StrictHostKeyChecking=no.
Every remote branch of sync builds its ssh command with that option, for password authentication, for private-key authentication and for the fallback. The ssh options a caller sets through set_openssh_opt reach the OpenSSH transport but not this command, so there is no configuration that restores host key checking for the transfer.
An attacker who can redirect the connection before the real host key is known presents their own and the transfer proceeds: under password authentication sync sends the connection password to that server, an upload writes the selected local files to it, and a download writes what it returns to the local destination.
| Weakness | CWE-322 : Key Exchange without Entity Authentication |
|---|
Product status
Known affected
| Product | Score | ||||
|---|---|---|---|---|---|
| Rex greater than 0 |
|
giterlizzi
Namespace: https://github.com/giterlizzi/
gdt@cpan.org
References
- CPANSA-Rex-2026-94140 JSON self
https://raw.githubusercontent.com/giterlizzi/perl-CPANSA-CSAF/develop/csaf/white/2026/cpansa-rex-2026-94140.json - https://metacpan.org/release/FERKI/Rex-1.16.1/source/lib/Rex/Commands/Rsync.pm external
https://metacpan.org/release/FERKI/Rex-1.16.1/source/lib/Rex/Commands/Rsync.pm - http://www.openwall.com/lists/oss-security/2026/10/21/28 external
http://www.openwall.com/lists/oss-security/2026/10/21/28 - CVE-2026-94140 (NVD) external
https://nvd.nist.gov/vuln/detail/CVE-2026-94140
Revision history
| Version | Date of the revision | Summary of the revision |
|---|---|---|
| 1 | Wed Oct 21 00:00:00 2026 | First release |
Sharing rules
TLP:WHITE
For the TLP version see: https://www.first.org/tlp/