MOKSHA-2026-0012 (moksha-2026-0012)

Vulnerability from moksha – Published: 2026-04-24 06:00 – Updated:
VLAI
Title
OVS Fail-Mode Denial of Service via Network.other_config
Summary
A pool-operator in XAPI-based hypervisors (XenServer, XCP-ng) can cause a complete network denial of service on any OVS bridge by setting Network.other_config:vswitch-controller-fail-mode to secure. In secure fail mode, OVS drops all packets when no SDN controller is reachable. Since most XAPI deployments do not configure an SDN controller, this immediately drops all traffic on the bridge, affecting every VM and management connection on that network.
CWE
  • CWE-862 - Missing Authorization
  • CWE-20 - Improper Input Validation
References
Impacted products
Credits
Jakob Wolffhechel, Moksha
Show details on NVD website

{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "XenServer",
          "vendor": "Cloud Software Group",
          "versions": [
            {
              "status": "affected",
              "version": "all",
              "versionType": "custom"
            }
          ]
        },
        {
          "product": "XCP-ng",
          "vendor": "Vates",
          "versions": [
            {
              "status": "affected",
              "version": "all",
              "versionType": "custom"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Jakob Wolffhechel, Moksha"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "A pool-operator in XAPI-based hypervisors (XenServer, XCP-ng) can cause a complete network denial of service on any OVS bridge by setting Network.other_config:vswitch-controller-fail-mode to secure. In secure fail mode, OVS drops all packets when no SDN controller is reachable. Since most XAPI deployments do not configure an SDN controller, this immediately drops all traffic on the bridge, affecting every VM and management connection on that network."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.2,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:N/A:H",
            "version": "3.1"
          },
          "format": "CVSS"
        },
        {
          "cvssV4_0": {
            "baseScore": 8.2,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H",
            "version": "4.0"
          },
          "format": "CVSS"
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-862",
              "description": "Missing Authorization",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-20",
              "description": "Improper Input Validation",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-04-24T06:00:00Z",
        "orgId": "moksha.dk",
        "shortName": "Moksha"
      },
      "references": [
        {
          "url": "https://cna.moksha.dk/MOKSHA-2026-0012"
        }
      ],
      "title": "OVS Fail-Mode Denial of Service via Network.other_config"
    }
  },
  "cveMetadata": {
    "alternateIds": [
      "GCVE-117-2026-0012"
    ],
    "assignerOrgId": "moksha.dk",
    "cveId": "MOKSHA-2026-0012",
    "datePublished": "2026-04-24T06:00:00Z",
    "state": "PUBLISHED",
    "x_moksha_note": "Self-issued advisory. MOKSHA-2026-NNNN is not a MITRE CVE ID. Schema follows CVE JSON 5.1 for tooling compatibility. alternateIds contains GCVE cross-references (GNA #117) and will also carry MITRE CVE IDs if assigned."
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1"
}


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