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Medium

Fleet doesn’t validate a server’s certificate when connecting through SSH

Type: advisorySources: OSV

A vulnerability has been identified within Fleet where, by default, Fleet will automatically trust a remote server’s certificate when connecting through SSH if the certificate isn’t set in the `known_hosts` file. This could allow the execution of a man-in-the-middle (MitM) attack against Fleet. In case the server that is being connected to has a trusted entry in the known_hosts file, then Fleet will correctly check the authenticity of the presented certificate.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2025-23390
Confirmed fixed CVEs
Not specified
Updated in this feed
7 Nov 2026, 16:44 UTC · Revision 1

Source evidence

Fleet doesn’t validate a server’s certificate when connecting through SSH

core-osv · Original source

Published 15 Oct 2026, 08:16 UTC

A vulnerability has been identified within Fleet where, by default, Fleet will automatically trust a remote server’s certificate when connecting through SSH if the certificate isn’t set in the `known_hosts` file. This could allow the execution of a man-in-the-middle (MitM) attack against Fleet. In case the server that is being connected to has a trusted entry in the known_hosts file, then Fleet will correctly check the authenticity of the presented certificate.

osv:CVE-2025-23390
Complete source record
{
  "id": "c2ea5f6a76d4daf231850e6d9e95497a4f7cfb17363ab701d732846d76bf766a",
  "url": "https://osv.dev/vulnerability/CVE-2025-23390",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Fleet doesn’t validate a server’s certificate when connecting through SSH",
    "summary": "A vulnerability has been identified within Fleet where, by default, Fleet will automatically trust a remote server’s certificate when connecting through SSH if the certificate isn’t set in the `known_hosts` file. This could allow the execution of a man-in-the-middle (MitM) attack against Fleet. In case the server that is being connected to has a trusted entry in the known_hosts file, then Fleet will correctly check the authenticity of the presented certificate.",
    "evidence": "osv:CVE-2025-23390",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2025-23390",
      "aliases": [
        "CVE-2025-23390",
        "GHSA-xgpc-q899-67p8",
        "GO-2025-3649"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/rancher/fleet",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0d26f206b3c521fdb78218285ffb69a91c6e5c81"
                },
                {
                  "fixed": "1dd9dd2074db8f1f9478b9b2fb046eba0a2539e4"
                },
                {
                  "introduced": "3e91ed3fb600e6499107751f7c3c0ab255f09640"
                },
                {
                  "fixed": "4809cf03c8926d834067bf1111ea24df6b875c32"
                },
                {
                  "introduced": "3d1fa6c06ff392c9fa66ca2f46831e2dae23bc16"
                },
                {
                  "fixed": "fcb09948fb937f043ab421b2b7ef03d7cbcce02b"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0.9.0-rc.1"
                      },
                      {
                        "fixed": "0.10.12"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  },
                  {
                    "range": [
                      {
                        "introduced": "0.11.0"
                      },
                      {
                        "fixed": "0.11.7"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  },
                  {
                    "range": [
                      {
                        "introduced": "0.12.0"
                      },
                      {
                        "fixed": "0.12.2"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v0.10.11-rc.1",
            "v0.10.11",
            "pkg/apis/v0.10.11-rc.1",
            "pkg/apis/v0.10.11",
            "v0.11.6-rc.2",
            "v0.11.6",
            "pkg/apis/v0.11.6",
            "v0.12.1-rc.1",
            "v0.12.1",
            "pkg/apis/v0.12.1-rc.1",
            "pkg/apis/v0.12.1",
            "v0.11.6-rc.1",
            "pkg/apis/v0.11.6-rc.1",
            "v0.10.11-beta.2",
            "v0.11.6-beta.2",
            "v0.12.1-beta.2",
            "v0.10.11-beta.1",
            "pkg/apis/v0.10.11-beta.1",
            "v0.11.6-beta.1",
            "pkg/apis/v0.11.6-beta.1",
            "v0.12.1-beta.1",
            "pkg/apis/v0.12.1-beta.1",
            "v0.10.10",
            "v0.11.5",
            "v0.12.0-rc.5",
            "v0.12.0",
            "pkg/apis/v0.12.0-rc.5",
            "pkg/apis/v0.12.0",
            "v0.10.9-rc.2",
            "v0.10.9",
            "v0.11.4",
            "v0.11.4-rc.2",
            "v0.11.4-rc.1",
            "v0.10.9-rc.1",
            "v0.11.3-rc.2",
            "v0.11.3",
            "pkg/apis/v0.11.3",
            "v0.10.8-rc.2",
            "v0.10.8",
            "pkg/apis/v0.10.8",
            "v0.10.8-rc.1",
            "v0.11.3-rc.1",
            "v0.10.8-beta.1",
            "pkg/apis/v0.10.8-beta.1",
            "v0.11.3-beta.1",
            "pkg/apis/v0.11.3-beta.1",
            "v0.10.7-rc.2",
            "v0.10.7",
            "v0.11.2-rc.2",
            "v0.11.2",
            "v0.11.2-rc.1",
            "v0.11.1-rc.3",
            "v0.11.1-rc.2",
            "v0.11.1-rc.1",
            "v0.11.1",
            "v0.10.7-rc.1",
            "v0.10.6-rc.1",
            "v0.10.6",
            "v0.11.0-rc.4",
            "v0.11.0",
            "pkg/apis/v0.11.0-rc.4",
            "pkg/apis/v0.11.0",
            "v0.10.5-rc.3",
            "v0.10.5",
            "v0.10.4-rc.4",
            "v0.10.4",
            "v0.10.5-rc.2",
            "v0.10.5-rc.1",
            "v0.10.4-rc.3",
            "v0.10.4-rc.2",
            "v0.10.4-rc.1",
            "v0.10.2-rc.4",
            "v0.10.2",
            "v0.10.3-rc.1",
            "v0.10.2-rc.3",
            "v0.10.2-rc.2",
            "v0.10.2-rc.1",
            "v0.10.1-rc.3",
            "v0.10.1",
            "v0.10.0-rc.21",
            "pkg/apis/v0.10.0-rc.21",
            "v0.10.0-rc.20",
            "pkg/apis/v0.10.0-rc.20",
            "v0.10.0-rc.19",
            "pkg/apis/v0.10.0-rc.19",
            "v0.10.0-rc.18",
            "v0.10.0-rc.17",
            "v0.10.0-rc.16",
            "pkg/apis/v0.10.0-rc.16",
            "v0.10.0-rc.15",
            "pkg/apis/v0.10.0-rc.15",
            "v0.10.0-rc.14",
            "pkg/apis/v0.10.0-rc.14",
            "pkg/apis/v0.10.0-rc.13",
            "v0.10.0-rc.13",
            "v0.10.0-rc.12",
            "v0.10.0-rc.11",
            "v0.10.0-rc.10",
            "v0.10.0-rc.9",
            "v0.10.0-rc.8",
            "v0.10.0-rc.7",
            "v0.10.0-rc.6",
            "v0.10.0-rc.5",
            "v0.10.0-rc.4",
            "pkg/apis/v0.10.0-rc.4",
            "v0.10.0-rc.3",
            "v0.10.0-rc.2",
            "v0.10.0-rc.1",
            "v0.9.0-rc.4",
            "v0.9.0-rc.3",
            "v0.9.0-rc.2",
            "v0.9.0-rc.1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-23390.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:51.056327742Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/23xxx/CVE-2025-23390.json",
        "https://github.com/rancher/fleet/security/advisories/GHSA-xgpc-q899-67p8",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-23390",
        "https://bugzilla.suse.com/show_bug.cgi?id=CVE-2025-23390"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-295"
        ],
        "cna_assigner": "suse",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/23xxx/CVE-2025-23390.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2025-23390",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 519899,
  "published_at": "2026-10-15T08:16:46.096+00:00"
}