CVE-2026-71887

{
  "etk_id": "ETK-2026-440",
  "cve_id": "CVE-2026-71887",
  "display_id": "CVE-2026-71887",
  "ghsa_id": "GHSA-cwf6-pghv-hq93",
  "euvd_id": "EUVD-2026-91993",
  "status": "published",
  "anchor_state": "anchored",
  "title": "Improper OpenPGP subkey binding validation in bcpg",
  "summary": "bcpg versions before 1.86 can associate a genuine OpenPGP subkey signature with an attacker-controlled certificate identity when applications use the high-level API. Exploitation requires a verifier to process a crafted certificate containing a public signing subkey and a message genuinely signed by that subkey; it does not enable creation of new signatures.",
  "mitigation": "Upgrade bcpg to version 1.86 or later. Until then, do not derive signer identity from an enclosing certificate when using the affected high-level API; make trust decisions using the signing subkey fingerprint.",
  "vendor": "Legion of the Bouncy Castle Inc.",
  "product": "BC-JAVA",
  "affected": [
    {
      "affected_notes": [],
      "affected_ranges": [
        ">= 1.81, < 1.86"
      ],
      "ecosystem": null,
      "fixed_versions": [
        "1.86"
      ],
      "package_name": "bcpg",
      "purl": null
    }
  ],
  "cwes": [
    347
  ],
  "cvss_score": 8.2,
  "cvss_src": "cna_vendor",
  "cvss_vector": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/U:Amber",
  "epss_score": 0.0009,
  "epss_percentile": 0.0042,
  "epss_asof": "2026-10-20",
  "automation": "contextual",
  "check": true,
  "check_confidence_basis": "mechanism_verified",
  "exploit": false,
  "pipeline_minutes": 17.670085983333333,
  "t0_at": "2026-10-03T08:39:07.997000+00:00",
  "signals": {
    "check": {
      "at": "2026-10-03T11:40:54.924593+00:00",
      "days": 0.12623758788194445,
      "is_lower_bound": false,
      "measured_at": "2026-10-03T08:39:07.997000+00:00",
      "url": null
    },
    "trigger_signal": {
      "at": "2026-10-03T08:39:07.997000+00:00",
      "days": 0,
      "is_lower_bound": false,
      "measured_at": "2026-10-03T08:39:07.997000+00:00",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-71887"
    }
  }
}