{
  "cveId": "CVE-2026-34876",
  "url": "https://patchblox.com/security/cve/CVE-2026-34876",
  "summary": "CVE-2026-34876 is fixed in mbedtls on 1 platform, first by DEBIAN-CVE-2026-34876, released April 2, 2026. It is not reported as exploited. Patch Radar priority: High.",
  "title": "mbedtls: An issue was discovered in Mbed TLS 3.x before 3.6.6",
  "description": "An issue was discovered in Mbed TLS 3.x before 3.6.6. An out-of-bounds read vulnerability in mbedtls_ccm_finish() in library/ccm.c allows attackers to obtain adjacent CCM context data via invocation of the multipart CCM API with an oversized tag_len parameter. This is caused by missing validation of the tag_len parameter against the size of the internal 16-byte authentication buffer. The issue affects the public multipart CCM API in Mbed TLS 3.x, where mbedtls_ccm_finish() can be invoked directly by applications. In Mbed TLS 4.x versions prior to the fix, the same missing validation exists in the internal implementation; however, the function is not exposed as part of the public API. Exploitation requires application-level invocation of the multipart CCM API.",
  "published": "2026-04-02T16:16:26Z",
  "severity": "high",
  "cvss": 7.5,
  "cvssVector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
  "epss": 0.00406,
  "epssPercentile": 0.35076,
  "priority": "High",
  "priorityTier": 3,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "mbedtls",
      "release": "Debian 13.5 (trixie)",
      "fixedVersion": "3.6.6-0.1~deb13u1",
      "fix": "DEBIAN-CVE-2026-34876",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-34876",
      "released": "2026-04-02T16:16:26Z"
    },
    {
      "platform": "linux",
      "product": "mbedtls",
      "release": "Debian 14",
      "fixedVersion": "3.6.6-0.1",
      "fix": "DEBIAN-CVE-2026-34876",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-34876",
      "released": "2026-04-02T16:16:26Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-08T00:53:09Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}