Application denial of service via out-of-bounds read in BSON Regex decoding in MongoDB Python Driver

{
  "id": "76935fe3b2ded438628e7efc7edd8fbc4843db2e3c22ffe17f558e3a50476fe3",
  "url": "https://osv.dev/vulnerability/CVE-2026-106435",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Application denial of service via out-of-bounds read in BSON Regex decoding in MongoDB Python Driver",
    "summary": "The MongoDB Python Driver's binary accelerator can read outside a buffer when an application decodes malformed BSON containing a truncated regular-expression element without a trailing NUL byte. An actor who can supply BSON to the documented decode or decode_all API can cause the application process to terminate when the C extension is loaded. The driver's normal database wire-protocol path does not reach this code.",
    "evidence": "osv:CVE-2026-106435",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-106435",
      "aliases": [
        "CVE-2026-106435",
        "GHSA-98qm-wvgf-w4cf"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/mongodb/mongo-python-driver",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "5479af6315dea9bd575bb374f72b645dfacbb3c3"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:mongodb:python_driver:*:*:*:*:*:mongodb:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "4.18.3"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
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              }
            }
          ],
          "versions": [
            "4.18.2",
            "4.18.1",
            "4.18.0",
            "4.16.0",
            "4.16.0.dev0",
            "4.15.1",
            "4.15.0",
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          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-106435.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:38.734544464Z",
      "provider": "osv",
      "references": [
        "https://jira.mongodb.org/browse/PYTHON-6110",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/106xxx/CVE-2026-106435.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-106435"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-125"
        ],
        "cna_assigner": "mongodb",
        "unresolved_ranges": [
          {
            "extracted_events": [
              {
                "range": [
                  {
                    "introduced": "0.10.3"
                  },
                  {
                    "last_affected": "4.18.2"
                  }
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                "source": "AFFECTED_FIELD",
                "strategy": "StandardRange"
              }
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        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/106xxx/CVE-2026-106435.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-106435",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 506306,
  "published_at": "2026-10-08T20:12:15.074+00:00"
}