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FKIE_CVE-2026-85769

Vulnerability from fkie_nvd - Published: 2026-09-04 18:18 - Updated: 2026-09-04 19:17
Severity
6.5 (Medium) - CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Summary
A flaw was found in libtpms, a library that provides software TPM 2.0 emulation. When restoring TPM 2.0 state (for example during a virtual machine's power-on or state/migration restore), a malformed state blob can supply an oversized skip-block length that is not validated against the remaining size of the input buffer. This can drive an internal size counter negative, which bypasses a subsequent bounds check due to an unsafe signed-to-unsigned conversion, causing the parser to read memory outside the bounds of the heap buffer holding the state data. Successful exploitation can crash the process hosting libtpms (such as swtpm), resulting in a denial of service of the emulated TPM device and the virtual machine that depends on it. No data corruption or information disclosure was confirmed.
References
secalert@redhat.comhttps://access.redhat.com/security/cve/CVE-2026-85769
secalert@redhat.comhttps://bugzilla.redhat.com/show_bug.cgi?id=2528538
secalert@redhat.comhttps://github.com/stefanberger/libtpms/commit/b1462888180d896af03cae0487e8d45009cc445e
secalert@redhat.comhttps://github.com/stefanberger/libtpms/issues/614
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/o:redhat:enterprise_linux:10"
          ],
          "defaultStatus": "affected",
          "packageName": "libtpms",
          "product": "Red Hat Enterprise Linux 10",
          "vendor": "Red Hat"
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/o:redhat:enterprise_linux:8"
          ],
          "defaultStatus": "affected",
          "packageName": "virt:rhel/libtpms",
          "product": "Red Hat Enterprise Linux 8",
          "vendor": "Red Hat"
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/o:redhat:enterprise_linux:9"
          ],
          "defaultStatus": "affected",
          "packageName": "libtpms",
          "product": "Red Hat Enterprise Linux 9",
          "vendor": "Red Hat"
        }
      ],
      "source": "secalert@redhat.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "A flaw was found in libtpms, a library that provides software TPM 2.0 emulation. When restoring TPM 2.0 state (for example during a virtual machine\u0027s power-on or state/migration restore), a malformed state blob can supply an oversized skip-block length that is not validated against the remaining size of the input buffer. This can drive an internal size counter negative, which bypasses a subsequent bounds check due to an unsafe signed-to-unsigned conversion, causing the parser to read memory outside the bounds of the heap buffer holding the state data. Successful exploitation can crash the process hosting libtpms (such as swtpm), resulting in a denial of service of the emulated TPM device and the virtual machine that depends on it. No data corruption or information disclosure was confirmed."
    }
  ],
  "id": "CVE-2026-85769",
  "lastModified": "2026-09-04T19:17:34.020",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "ADJACENT_NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 6.5,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 3.6,
        "source": "secalert@redhat.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-85769",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-09-04T18:51:03.667125Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-09-04T18:18:07.153",
  "references": [
    {
      "source": "secalert@redhat.com",
      "url": "https://access.redhat.com/security/cve/CVE-2026-85769"
    },
    {
      "source": "secalert@redhat.com",
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2528538"
    },
    {
      "source": "secalert@redhat.com",
      "url": "https://github.com/stefanberger/libtpms/commit/b1462888180d896af03cae0487e8d45009cc445e"
    },
    {
      "source": "secalert@redhat.com",
      "url": "https://github.com/stefanberger/libtpms/issues/614"
    }
  ],
  "sourceIdentifier": "secalert@redhat.com",
  "vulnStatus": "Received",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-125"
        }
      ],
      "source": "secalert@redhat.com",
      "type": "Secondary"
    }
  ]
}



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