Rex versions through 1.16.1 for Perl accept an unknown SSH host key for remote rsync transfers because sync hardcodes StrictHostKeyChecking=no

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-94140
StatePUBLISHED
AssignerCPANSec
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-21 22:16:50 UTC
Updated2026-10-30 16:18:00 UTC
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.

Risk And Classification

Primary CVSS: v3.1 9.1 CRITICAL from ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

EPSS: 0.004280000 probability, percentile 0.371120000 (date 2026-11-01)

Problem Types: CWE-322 | CWE-322 CWE-322 Key Exchange without Entity Authentication

VersionSourceTypeScoreSeverityVector
3.1ADPDECLARED9.1CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary9.1CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

References

ReferenceSourceLinkTags
metacpan.org/release/FERKI/Rex-1.16.1/source/lib/Rex/Commands/Rsync.pm 9b29abf9-4ab0-4765-b253-1875cd9b441e metacpan.org
www.openwall.com/lists/oss-security/2026/10/21/28 af854a3a-2127-422b-91ae-364da2661108 www.openwall.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: James Klein (en)

Additional Advisory Data

Solutions

CNA: No fixed CPAN release is currently available.

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