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

Type: advisorySources: OSV

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.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2026-94140
Confirmed fixed CVEs
Not specified
Updated in this feed
7 Nov 2026, 17:55 UTC · Revision 1

Source evidence

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

core-osv · Original source

Published 21 Oct 2026, 21:22 UTC

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.

osv:CVE-2026-94140
Complete source record
{
  "id": "f34eb643b18d32c4e04f1b81db597fcd30128835527aa1a8688e572472a43bf9",
  "url": "https://osv.dev/vulnerability/CVE-2026-94140",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Rex versions through 1.16.1 for Perl accept an unknown SSH host key for remote rsync transfers because sync hardcodes StrictHostKeyChecking=no",
    "summary": "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.",
    "evidence": "osv:CVE-2026-94140",
    "products": [],
    "severity": "critical",
    "structured": {
      "id": "CVE-2026-94140",
      "aliases": [
        "CVE-2026-94140"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/rexops/rex",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "last_affected": "7fc0fd354cc54698a961d749eab63b53593bd2ae"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "last_affected": "1.16.1"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  }
                ]
              }
            }
          ],
          "versions": [
            "1.16.1",
            "1.16.0.3",
            "1.16.0.2",
            "1.16.0.1",
            "1.16.0",
            "1.15.0.2",
            "1.15.0.1",
            "1.15.0",
            "1.14.3.2",
            "1.14.3.1",
            "1.14.3",
            "1.14.2.3",
            "1.14.2.2",
            "1.14.2.1",
            "1.14.2",
            "1.14.1",
            "1.14.0.1",
            "1.14.0",
            "1.13.4.1",
            "1.13.4",
            "1.13.3.2",
            "1.13.3.1",
            "1.13.3",
            "1.13.2",
            "1.13.1",
            "1.13.0.3",
            "1.13.0.2",
            "1.13.0.1",
            "1.13.0",
            "1.12.2.3",
            "1.12.2.2",
            "1.12.2.1",
            "1.12.2",
            "1.12.1.3",
            "1.12.1.2",
            "1.12.1.1",
            "1.12.1",
            "1.12.0.1",
            "1.12.0",
            "1.11.0.4",
            "1.11.0.3",
            "1.11.0.2",
            "1.11.0.1",
            "1.11.0",
            "1.10.0.1",
            "1.10.0",
            "1.9.0",
            "1.8.2_02",
            "1.8.2_01",
            "1.8.2",
            "1.8.1",
            "1.8.0_01",
            "1.3.3",
            "1.3.1",
            "1.3.0",
            "1.3.0-rc1",
            "1.2.0",
            "1.1.0",
            "1.0.0",
            "0.57.0",
            "0.56.0",
            "0.55.3",
            "0.55.2",
            "0.55.1",
            "0.55.0",
            "0.54.3",
            "0.54.1",
            "0.52.1",
            "0.52.0",
            "0.51.2",
            "0.51.1",
            "0.50.0",
            "0.49.1",
            "0.46.0",
            "0.44.3",
            "0.44.2",
            "0.44.1",
            "0.44.0",
            "0.43.2",
            "0.42.2",
            "0.42.1",
            "0.42.0",
            "0.41.1",
            "0.41.0",
            "0.40.4",
            "0.40.3",
            "0.40.2",
            "0.40.1",
            "0.40.0",
            "0.39.0",
            "0.38.0",
            "0.37.0",
            "0.35.1",
            "0.34.1",
            "0.34.0",
            "0.33.1",
            "0.31.4",
            "0.30.0",
            "0.29.0",
            "0.26.1",
            "0.26.0",
            "0.25.3",
            "0.25.2",
            "0.24.1",
            "0.24.0",
            "0.22.0",
            "0.18.0",
            "0.17.0",
            "0.15.0",
            "0.14.0",
            "0.13.0",
            "0.11.0",
            "0.10.0.2",
            "0.9.0",
            "0.8.0",
            "0.7.1",
            "0.7.0",
            "0.5.0",
            "0.4.2",
            "0.4.1",
            "0.4.0",
            "0.3.1",
            "0.3.0",
            "0.2.2",
            "0.2.1",
            "0.2.0",
            "0.1.2",
            "0.1.0",
            "0.0.5",
            "0.0.4",
            "0.0.3",
            "0.0.2",
            "0.0.1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-94140.json"
          }
        }
      ],
      "modified": "2026-11-01T02:30:31.095590227Z",
      "provider": "osv",
      "references": [
        "https://cpan.org/modules",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/94xxx/CVE-2026-94140.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-94140",
        "https://github.com/RexOps/Rex",
        "https://metacpan.org/release/FERKI/Rex-1.16.1/source/lib/Rex/Commands/Rsync.pm"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-322"
        ],
        "cna_assigner": "CPANSec",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/94xxx/CVE-2026-94140.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-94140",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 520032,
  "published_at": "2026-10-21T21:22:19.577+00:00"
}