Integer overflow in libmime buffer growth could lead to heap corruption

{
  "id": "7b60390dc59583231a6b2aec32532aad3fdd2039010238529c3840c5ada19804",
  "url": "https://www.cve.org/CVERecord?id=CVE-2026-110247",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Integer overflow in libmime buffer growth could lead to heap corruption",
    "summary": "Several buffer-growth sites in libmime performed size arithmetic in 32-bit types without overflow checks. On a sufficiently large message the growth guard could fail open, or the buffer could be reallocated smaller than required, and a subsequent memcpy would then write attacker-controlled data across adjacent heap allocations. This vulnerability was fixed in Thunderbird 158 and Thunderbird 153.6.",
    "evidence": "cve:CVE-2026-110247",
    "products": [
      {
        "name": {
          "value": "Thunderbird",
          "evidence": "/containers/cna/affected/0/product"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-110247",
      "aliases": [
        "CVE-2026-110247"
      ],
      "metrics": [],
      "affected": [
        {
          "vendor": "Mozilla",
          "product": "Thunderbird",
          "versions": [
            {
              "status": "unaffected",
              "version": "153.6",
              "versionType": "rpm",
              "lessThanOrEqual": "153.*"
            },
            {
              "status": "unaffected",
              "version": "158",
              "versionType": "rpm",
              "lessThanOrEqual": "*"
            }
          ]
        }
      ],
      "modified": "2026-10-27T18:27:45.455Z",
      "provider": "cve",
      "references": [
        "https://bugzilla.mozilla.org/show_bug.cgi?id=2071621",
        "https://www.mozilla.org/security/advisories/mfsa2026-109/",
        "https://www.mozilla.org/security/advisories/mfsa2026-122/"
      ],
      "provider_metadata": {
        "adp": [
          {
            "title": "CISA ADP Vulnrichment",
            "metrics": [
              {
                "cvssV3_1": {
                  "scope": "UNCHANGED",
                  "version": "3.1",
                  "baseScore": 8.4,
                  "attackVector": "LOCAL",
                  "baseSeverity": "HIGH",
                  "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
                  "integrityImpact": "HIGH",
                  "userInteraction": "NONE",
                  "attackComplexity": "LOW",
                  "availabilityImpact": "HIGH",
                  "privilegesRequired": "NONE",
                  "confidentialityImpact": "HIGH"
                }
              },
              {
                "other": {
                  "type": "ssvc",
                  "content": {
                    "id": "CVE-2026-110247",
                    "role": "CISA Coordinator",
                    "options": [
                      {
                        "Exploitation": "none"
                      },
                      {
                        "Automatable": "no"
                      },
                      {
                        "Technical Impact": "total"
                      }
                    ],
                    "version": "2.0.3",
                    "timestamp": "2026-10-20T17:08:54.337976Z"
                  }
                }
              }
            ],
            "problemTypes": [
              {
                "descriptions": [
                  {
                    "lang": "en",
                    "type": "CWE",
                    "cweId": "CWE-190",
                    "description": "CWE-190 Integer Overflow or Wraparound"
                  }
                ]
              }
            ],
            "providerMetadata": {
              "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "shortName": "CISA-ADP",
              "dateUpdated": "2026-10-20T17:09:29.220Z"
            }
          }
        ],
        "cna": {
          "orgId": "f16b083a-5664-49f3-a51e-8d479e5ed7fe",
          "shortName": "mozilla",
          "dateUpdated": "2026-10-27T18:27:45.455Z"
        }
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-110247",
        "evidence": "/cveMetadata/cveId"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-cve",
  "document_id": 397815,
  "published_at": "2026-10-13T18:08:37.608+00:00"
}