{
  "cveId": "CVE-2023-4421",
  "url": "https://patchblox.com/security/cve/CVE-2023-4421",
  "summary": "CVE-2023-4421 is fixed in 3 products on 1 platform, first by DEBIAN-CVE-2023-4421, released December 12, 2023. It is not reported as exploited. Patch Radar priority: Routine.",
  "title": "libnss3: The NSS code used for checking PKCS#1 v1.5 was leaking information useful in mounting Bleichenbacher-like attacks",
  "description": "The NSS code used for checking PKCS#1 v1.5 was leaking information useful in mounting Bleichenbacher-like attacks. Both the overall correctness of the padding as well as the length of the encrypted message was leaking through timing side-channel. By sending large number of attacker-selected ciphertexts, the attacker would be able to decrypt a previously intercepted PKCS#1 v1.5 ciphertext (for example, to decrypt a TLS session that used RSA key exchange), or forge a signature using the victim\u0027s key. The issue was fixed by implementing the implicit rejection algorithm, in which the NSS returns a deterministic random message in case invalid padding is detected, as proposed in the Marvin Attack paper. This vulnerability affects NSS \u0026lt; 3.61.",
  "published": "2023-12-12T09:15:00Z",
  "severity": "Medium",
  "cvss": 6.5,
  "cvssVector": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N",
  "epss": 0.00762,
  "epssPercentile": 0.55673,
  "priority": "Routine",
  "priorityTier": 4,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "libnss3",
      "release": "Ubuntu 20.04 LTS (focal)",
      "fixedVersion": "2:3.98-0ubuntu0.20.04.1",
      "fix": "libnss3 2:3.98-0ubuntu0.20.04.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-focal-libnss3-2-3.98-0ubuntu0.20.04.1",
      "released": "2023-12-19T16:00:00Z"
    },
    {
      "platform": "linux",
      "product": "libnss3-tools",
      "release": "Ubuntu 20.04 LTS (focal)",
      "fixedVersion": "2:3.98-0ubuntu0.20.04.1",
      "fix": "libnss3-tools 2:3.98-0ubuntu0.20.04.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-focal-libnss3-tools-2-3.98-0ubuntu0.20.04.1",
      "released": "2023-12-19T16:00:00Z"
    },
    {
      "platform": "linux",
      "product": "nss",
      "release": "Debian 12.15 (bookworm)",
      "fixedVersion": "2:3.61-1",
      "fix": "DEBIAN-CVE-2023-4421",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2023-4421",
      "released": "2023-12-12T17:15:08Z"
    },
    {
      "platform": "linux",
      "product": "nss",
      "release": "Debian 13.5 (trixie)",
      "fixedVersion": "2:3.61-1",
      "fix": "DEBIAN-CVE-2023-4421",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2023-4421",
      "released": "2023-12-12T17:15:08Z"
    },
    {
      "platform": "linux",
      "product": "nss",
      "release": "Debian 14",
      "fixedVersion": "2:3.61-1",
      "fix": "DEBIAN-CVE-2023-4421",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2023-4421",
      "released": "2023-12-12T17:15:08Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-11T07:45:43Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}