{
  "name": "Inside the Fix: Analysis of In-the-Wild Exploit of CVE-2026-21513",
  "slug": "inside-the-fix-analysis-of-in-the-wild-exploit-of-cve-2026-21513",
  "description": "This analysis examines CVE-2026-21513, a security bypass vulnerability in Microsoft's MSHTML framework, patched in February 2026. The flaw, actively exploited by Russian state-sponsored actor APT28, affects all Windows versions and has a CVSS score of 8.8. Using PatchDiff-AI, researchers identified the root cause in ieframe.dll's hyperlink navigation handling, allowing arbitrary file execution outside the browser's security context. The exploit involves a crafted Windows Shortcut file embedding HTML, communicating with APT28-linked infrastructure. It bypasses security measures like Mark of the Web and IE Enhanced Security Configuration through nested iframes and DOM manipulation, ultimately invoking ShellExecuteExW for out-of-sandbox execution.",
  "published": "2026-02-25T10:46:21+00:00",
  "created_at": "2026-02-25T10:46:21+00:00",
  "modified_at": "2026-02-25T10:56:53+00:00",
  "created_at_opencti": "2026-02-25T10:46:21+00:00",
  "author": "",
  "confidence": null,
  "report_types": [],
  "labels": [],
  "tags": [
    "2026-02-25",
    "CVE-2026-21513",
    "exploit",
    "ieframe.dll",
    "mshtml",
    "patchdiff-ai",
    "shellexecuteexw",
    "windows",
    "zero-day"
  ],
  "related_entities": {
    "observables": [
      {
        "id": "",
        "name": "aefd15e3c395edd16ede7685c6e97ca0350a702ee7c8585274b457166e86b1fa"
      }
    ],
    "intrusion_sets": [
      {
        "id": "2e5c75e1-c481-46c4-8d26-f0774a3457fa",
        "name": "APT28",
        "slug": "apt28"
      }
    ],
    "attack_patterns": [
      {
        "id": "16e4fc82-7c0b-4d1a-b784-b804b4df26dc",
        "name": "T1204.001"
      },
      {
        "id": "dc410646-9cdd-427b-92e7-179a54f78f90",
        "name": "T1566.001"
      }
    ],
    "vulnerabilities": [
      {
        "id": "",
        "name": "CVE-2026-21513"
      }
    ],
    "others": [
      {
        "id": "",
        "name": "Russian Federation"
      },
      {
        "id": "",
        "name": "wellnesscaremed.com"
      }
    ]
  },
  "external_refs": [
    "https://www.akamai.com/blog/security-research/2026/feb/inside-the-fix-cve-2026-21513-mshtml-exploit-analysis",
    "https://otx.alienvault.com/pulse/699ee10d4bfa4e5fcf71399d"
  ]
}