mbedtls — security advisory
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
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"
}