MOKSHA-2026-0018

Vulnerability from moksha – Published: 2026-04-24 06:00 – Updated:
VLAI
Title
HA Timeout Manipulation via Pool.other_config (Split-Brain/Blindness)
Summary
A pool-operator in XAPI-based hypervisors (XenServer, XCP-ng) can manipulate the High Availability timeout by setting Pool.other_config:default_ha_timeout to an arbitrary integer. The value is read by xapi_ha.ml via int_of_string with no range check. A timeout of 1 second causes spurious HA fencing events and cascading host reboots (split-brain). A timeout of 999999 seconds effectively disables HA, leaving host failures undetected for days and HA-protected VMs without failover. Both outcomes affect every HA-protected VM across the entire pool.
Severity
7.6 (High)
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:N/A:H
8.2 (High)
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
CWE
  • CWE-862 - Missing Authorization
  • CWE-20 - Improper Input Validation
References
Impacted products
Credits
Jakob Wolffhechel, Moksha
Show details on NVD website
To clipboard 

{
  "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 manipulate the High Availability timeout by setting Pool.other_config:default_ha_timeout to an arbitrary integer. The value is read by xapi_ha.ml via int_of_string with no range check. A timeout of 1 second causes spurious HA fencing events and cascading host reboots (split-brain). A timeout of 999999 seconds effectively disables HA, leaving host failures undetected for days and HA-protected VMs without failover. Both outcomes affect every HA-protected VM across the entire pool."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.6,
            "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-2026-0018"
        }
      ],
      "title": "HA Timeout Manipulation via Pool.other_config (Split-Brain/Blindness)"
    }
  },
  "cveMetadata": {
    "alternateIds": [
      "GCVE-117-2026-0018"
    ],
    "assignerOrgId": "moksha.dk",
    "cveId": "MOKSHA-2026-0018",
    "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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