CVE-2026-71890

{
  "etk_id": "ETK-2026-444",
  "cve_id": "CVE-2026-71890",
  "display_id": "CVE-2026-71890",
  "ghsa_id": "GHSA-jc55-7frr-fv5r",
  "euvd_id": "EUVD-2026-92006",
  "status": "published",
  "anchor_state": "anchored",
  "title": "Improper external commit validation in bcmls MLS",
  "summary": "bcmls versions before 1.86 incorrectly validate MLS external commits that request removal of a group member. An attacker with the group's public GroupInfo can cause another member to be removed and take over that member's ratchet-tree position.",
  "mitigation": "Upgrade bcmls to version 1.86 or later. Restrict distribution of public GroupInfo until all affected deployments are updated.",
  "vendor": "Legion of the Bouncy Castle Inc.",
  "product": "BC-JAVA",
  "affected": [
    {
      "affected_notes": [],
      "affected_ranges": [
        ">= 1.73, < 1.86"
      ],
      "ecosystem": null,
      "fixed_versions": [
        "1.86"
      ],
      "package_name": "bcmls",
      "purl": null
    }
  ],
  "cwes": [
    863
  ],
  "cvss_score": 8.7,
  "cvss_src": "cna_vendor",
  "cvss_vector": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/U:Amber",
  "epss_score": 0.0025,
  "epss_percentile": 0.152,
  "epss_asof": "2026-10-20",
  "automation": "contextual",
  "check": false,
  "check_confidence_basis": null,
  "exploit": false,
  "pipeline_minutes": 9.6902324,
  "t0_at": "2026-10-03T08:57:00.965000+00:00",
  "signals": {
    "trigger_signal": {
      "at": "2026-10-03T08:57:00.965000+00:00",
      "days": 0,
      "is_lower_bound": false,
      "measured_at": "2026-10-03T08:57:00.965000+00:00",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-71890"
    }
  }
}