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mbedtls — security advisory

Type: advisorySources: OSVAdvisory ID: DEBIAN-CVE-2020-36478

An issue was discovered in Mbed TLS before 2.25.0 (and before 2.16.9 LTS and before 2.7.18 LTS). A NULL algorithm parameters entry looks identical to an array of REAL (size zero) and thus the certificate is considered valid. However, if the parameters do not match in any way, then the certificate should be considered invalid.

Products
mbedtls
Affected versions
Not specified
Fixed versions
2.16.9-0.1
CVEs
CVE-2020-36478
Confirmed fixed CVEs
Not specified
Updated in this feed
1 Nov 2026, 13:14 UTC · Revision 1

Source evidence

DEBIAN-CVE-2020-36478

core-osv · Original source

Published 23 Aug 2021, 02:15 UTC

An issue was discovered in Mbed TLS before 2.25.0 (and before 2.16.9 LTS and before 2.7.18 LTS). A NULL algorithm parameters entry looks identical to an array of REAL (size zero) and thus the certificate is considered valid. However, if the parameters do not match in any way, then the certificate should be considered invalid.

osv:DEBIAN-CVE-2020-36478

mbedtls

Fixed versions: 2.16.9-0.1

mbedtls

Fixed versions: 2.16.9-0.1

mbedtls

Fixed versions: 2.16.9-0.1

Complete source record
{
  "id": "40277ad427ea24eaeef439e25bce4f6c07576c6abcb7362346e482a5c919a23a",
  "url": "https://osv.dev/vulnerability/DEBIAN-CVE-2020-36478",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "DEBIAN-CVE-2020-36478",
    "summary": "An issue was discovered in Mbed TLS before 2.25.0 (and before 2.16.9 LTS and before 2.7.18 LTS). A NULL algorithm parameters entry looks identical to an array of REAL (size zero) and thus the certificate is considered valid. However, if the parameters do not match in any way, then the certificate should be considered invalid.",
    "evidence": "osv:DEBIAN-CVE-2020-36478",
    "products": [
      {
        "name": {
          "value": "mbedtls",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "2.16.9-0.1",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      },
      {
        "name": {
          "value": "mbedtls",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "2.16.9-0.1",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      },
      {
        "name": {
          "value": "mbedtls",
          "evidence": "/affected/2/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "2.16.9-0.1",
            "evidence": "/affected/2/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "DEBIAN-CVE-2020-36478",
      "aliases": [
        "DEBIAN-CVE-2020-36478"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "2.16.9-0.1"
                }
              ]
            }
          ],
          "package": {
            "name": "mbedtls",
            "purl": "pkg:deb/debian/mbedtls?arch=source&distro=bookworm",
            "ecosystem": "Debian:12"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2020-36478.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "2.16.9-0.1"
                }
              ]
            }
          ],
          "package": {
            "name": "mbedtls",
            "purl": "pkg:deb/debian/mbedtls?arch=source&distro=trixie",
            "ecosystem": "Debian:13"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2020-36478.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "2.16.9-0.1"
                }
              ]
            }
          ],
          "package": {
            "name": "mbedtls",
            "purl": "pkg:deb/debian/mbedtls?arch=source&distro=forky",
            "ecosystem": "Debian:14"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2020-36478.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        }
      ],
      "modified": "2026-10-26T12:02:03.843251138Z",
      "provider": "osv",
      "upstream": [
        "CVE-2020-36478"
      ],
      "references": [
        "https://security-tracker.debian.org/tracker/CVE-2020-36478"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2020-36478",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 451984,
  "published_at": "2021-08-23T02:15:07.097+00:00"
}