CVE-2026-84783

{
  "etk_id": "ETK-2026-541",
  "cve_id": "CVE-2026-84783",
  "display_id": "CVE-2026-84783",
  "ghsa_id": "GHSA-2pj2-4hfp-vxp8",
  "euvd_id": "EUVD-2026-89014",
  "status": "published",
  "anchor_state": "anchored",
  "title": "Concurrent X.509 cache use-after-free in OpenSSL",
  "summary": "OpenSSL 4.0 can access freed X.509 extension-cache data during concurrent certificate validation. An unauthenticated remote peer may cause a multithreaded TLS client, or a server verifying client certificates, to terminate. Exposure requires several initial chain validations against the same trusted CA to occur concurrently.",
  "mitigation": "Upgrade OpenSSL 4.0 deployments to version 4.0.3. Until upgrades are complete, reduce exposure by avoiding concurrent initial validations that share trusted CA certificates.",
  "vendor": "OpenSSL",
  "product": "OpenSSL",
  "affected": [
    {
      "affected_notes": [],
      "affected_ranges": [
        ">= 4.0.0, < 4.0.3"
      ],
      "ecosystem": null,
      "fixed_versions": [
        "4.0.3"
      ],
      "package_name": "OpenSSL",
      "purl": null
    }
  ],
  "cwes": [
    416
  ],
  "cvss_score": 7.5,
  "cvss_src": "nvd",
  "cvss_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
  "epss_score": 0.0023,
  "epss_percentile": 0.1246,
  "epss_asof": "2026-10-20",
  "automation": "contextual",
  "check": false,
  "check_confidence_basis": null,
  "exploit": false,
  "pipeline_minutes": 23.5550975,
  "t0_at": "2026-09-29T15:32:24.699000+00:00",
  "signals": {
    "trigger_signal": {
      "at": "2026-09-29T15:32:24.699000+00:00",
      "days": 0,
      "is_lower_bound": false,
      "measured_at": "2026-09-29T15:32:24.699000+00:00",
      "url": "https://thehackernews.com/2026/09/openssl-fixes-high-severity-dtls-flaw.html"
    }
  }
}