CVE-2026-126186

{
  "etk_id": "ETK-2026-3520",
  "cve_id": "CVE-2026-126186",
  "display_id": "CVE-2026-126186",
  "ghsa_id": "GHSA-v924-7rp8-4mxh",
  "euvd_id": "EUVD-2026-122941",
  "status": "published",
  "anchor_state": "anchored",
  "title": "Unsafe filename extension handling in Active Storage",
  "summary": "Affected Active Storage releases can pass temporary upload files with attacker-controlled extensions to FFmpeg or ImageMagick. Applications that accept untrusted uploads and analyze media, generate video previews, or process images may cause unintended decoders to handle those files; AviSynth-enabled FFmpeg environments may expose application-readable data or permit code execution in the FFmpeg process.",
  "mitigation": "Upgrade activestorage to 8.0.5.2 or 8.1.4.1, as appropriate for the supported release line. Until upgrading, disable the Active Storage video previewer and video and audio analyzers to reduce FFmpeg exposure; also avoid FFmpeg builds with AviSynth support.",
  "vendor": "rubygems",
  "product": "rubygems:activestorage",
  "affected": [
    {
      "affected_notes": [],
      "affected_ranges": [
        ">= 8.1, < 8.1.4.1"
      ],
      "ecosystem": "rubygems",
      "fixed_versions": [
        "8.1.4.1"
      ],
      "package_name": "activestorage",
      "purl": "pkg:gem/activestorage"
    },
    {
      "affected_notes": [],
      "affected_ranges": [
        "< 8.0.5.2"
      ],
      "ecosystem": "rubygems",
      "fixed_versions": [
        "8.0.5.2"
      ],
      "package_name": "activestorage",
      "purl": "pkg:gem/activestorage"
    }
  ],
  "cwes": [
    646
  ],
  "cvss_score": 8.8,
  "cvss_src": "cna_vendor",
  "cvss_vector": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
  "epss_score": null,
  "epss_percentile": null,
  "epss_asof": null,
  "automation": "contextual",
  "check": true,
  "check_confidence_basis": "assessed",
  "exploit": false,
  "pipeline_minutes": 34.30277838333333,
  "t0_at": "2026-11-10T21:14:22.083000+00:00",
  "signals": {
    "check": {
      "at": "2026-11-04T16:54:47.416961+00:00",
      "days": -6.180262338414352,
      "is_lower_bound": false,
      "measured_at": "2026-11-10T21:14:22.083000+00:00",
      "url": null
    },
    "trigger_signal": {
      "at": "2026-11-04T03:02:13+00:00",
      "days": -6.758438460648148,
      "is_lower_bound": false,
      "measured_at": "2026-11-10T21:14:22.083000+00:00",
      "url": "https://github.com/rails/rails/security/advisories/GHSA-v924-7rp8-4mxh"
    }
  }
}