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CVE-2026-42495

Status: DeferredMedium (5.5)—

[This CNA information record relates to multiple CVEs; the text explains which aspects/vulnerabilities correspond to which CVE.]

The directory and Rock Ridge / SUSP walk in libfsimage's iso9660 driver derives several lengths directly from attacker-controlled on-disk fields without validating them:

Technical details traces, logs and code from the original report
 * The directory loop itself assumes a good record length.  This is
   CVE-2026-42494.

 * The calculation of the System Use area may underflow.  This is
   CVE-2026-42495.

 * The Rock Ridge extension loop assumes a good (inner) record length.
   This is CVE-2026-62423.

 * The Rock Ridge NM record processing assumes a good entry length.
   This is CVE-2026-62424.

 * The Rock Ridge CE record processing assumes a good size and offset.
   This is CVE-2026-62425.

CVSS

Exploitation probability (EPSS)

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

Affected technologies (1)

⚠ AI-inferred from the description — NVD hasn't analyzed this CVE yet, these aren't verified CPEs.

XEN — LibfsimageAI

CWEs

References

Raw JSON (NVD)

Show
{
  "id": "CVE-2026-42495",
  "cveTags": [],
  "metrics": {
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-42495",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2026-07-28T15:00:30.511503Z"
        }
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 5.5,
          "attackVector": "LOCAL",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H",
          "integrityImpact": "NONE",
          "userInteraction": "REQUIRED",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 1.8
      }
    ]
  },
  "affected": [
    {
      "source": "security@xen.org",
      "affectedData": [
        {
          "vendor": "Xen",
          "product": "Xen",
          "versions": [
            {
              "status": "unknown",
              "version": "consult Xen advisory XSA-497"
            }
          ],
          "defaultStatus": "unknown"
        }
      ]
    }
  ],
  "published": "2026-07-28T13:18:32.493",
  "references": [
    {
      "url": "https://xenbits.xenproject.org/xsa/advisory-497.html",
      "source": "security@xen.org"
    }
  ],
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "description": [
        {
          "lang": "en",
          "value": "CWE-191"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "[This CNA information record relates to multiple CVEs; the\ntext explains which aspects/vulnerabilities correspond to which CVE.]\n\nThe directory and Rock Ridge / SUSP walk in libfsimage's iso9660 driver\nderives several lengths directly from attacker-controlled on-disk fields\nwithout validating them:\n\n * The directory loop itself assumes a good record length.  This is\n   CVE-2026-42494.\n\n * The calculation of the System Use area may underflow.  This is\n   CVE-2026-42495.\n\n * The Rock Ridge extension loop assumes a good (inner) record length.\n   This is CVE-2026-62423.\n\n * The Rock Ridge NM record processing assumes a good entry length.\n   This is CVE-2026-62424.\n\n * The Rock Ridge CE record processing assumes a good size and offset.\n   This is CVE-2026-62425."
    }
  ],
  "lastModified": "2026-07-28T16:17:49.067",
  "sourceIdentifier": "security@xen.org"
}