CVE-2026-71885

{
  "etk_id": "ETK-2026-443",
  "cve_id": "CVE-2026-71885",
  "display_id": "CVE-2026-71885",
  "ghsa_id": "GHSA-jch3-5j66-88vx",
  "euvd_id": "EUVD-2026-92003",
  "status": "published",
  "anchor_state": "anchored",
  "title": "X.509 credential key-binding flaw in bcmls MLS",
  "summary": "bcmls versions before 1.86 can accept an MLS X.509 credential whose certificate key is not bound to the signing key. An unauthenticated party may impersonate a certificate holder and gain group access or send accepted messages when the deployment permits external commits without an independent credential-admission check. Deployments using only basic MLS credentials are not affected.",
  "mitigation": "Upgrade bcmls to version 1.86 or later. Independently validate certificate chains and identities against an appropriate trust anchor, and restrict external commits until such admission checks are enforced.",
  "vendor": "Legion of the Bouncy Castle Inc.",
  "product": "BC-JAVA",
  "affected": [
    {
      "affected_notes": [],
      "affected_ranges": [
        ">= 0, < 1.86"
      ],
      "ecosystem": null,
      "fixed_versions": [
        "1.86"
      ],
      "package_name": "bcmls",
      "purl": null
    }
  ],
  "cwes": [
    295
  ],
  "cvss_score": 9.2,
  "cvss_src": "cna_vendor",
  "cvss_vector": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N/U:Amber",
  "epss_score": 0.0019,
  "epss_percentile": 0.0787,
  "epss_asof": "2026-10-20",
  "automation": "contextual",
  "check": true,
  "check_confidence_basis": "assessed",
  "exploit": false,
  "pipeline_minutes": 10.5883235,
  "t0_at": "2026-10-03T08:51:53.292000+00:00",
  "signals": {
    "check": {
      "at": "2026-10-03T09:48:45.911484+00:00",
      "days": 0.039497910694444444,
      "is_lower_bound": false,
      "measured_at": "2026-10-03T08:51:53.292000+00:00",
      "url": null
    },
    "trigger_signal": {
      "at": "2026-10-03T08:51:53.292000+00:00",
      "days": 0,
      "is_lower_bound": false,
      "measured_at": "2026-10-03T08:51:53.292000+00:00",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-71885"
    }
  }
}