mbedtls — security advisory
Use of a Broken or Risky Cryptographic Algorithm in the function mbedtls_mpi_exp_mod() in lignum.c in Mbed TLS Mbed TLS all versions before 3.0.0, 2.27.0 or 2.16.11 allows attackers with access to precise enough timing and memory access information (typically an untrusted operating system attacking a secure enclave such as SGX or the TrustZone secure world) to recover the private keys used in RSA.
- Products
- mbedtls
- Affected versions
- Not specified
- Fixed versions
- 2.16.11-0.1
- CVEs
- CVE-2021-36647
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 1 Nov 2026, 02:01 UTC · Revision 1
Source evidence
Use of a Broken or Risky Cryptographic Algorithm in the function mbedtls_mpi_exp_mod() in lignum.c in Mbed TLS Mbed TLS all versions before 3.0.0, 2.27.0 or 2.16.11 allows attackers with access to precise enough timing and memory access information (typically an untrusted operating system attacking a secure enclave such as SGX or the TrustZone secure world) to recover the private keys used in RSA.
osv:DEBIAN-CVE-2021-36647
mbedtls
Fixed versions: 2.16.11-0.1
mbedtls
Fixed versions: 2.16.11-0.1
mbedtls
Fixed versions: 2.16.11-0.1
Complete source record
{
"id": "cd999affeb5d7f48b2502810e13e7daac671194438a540256602a7ceac20070a",
"url": "https://osv.dev/vulnerability/DEBIAN-CVE-2021-36647",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "DEBIAN-CVE-2021-36647",
"summary": "Use of a Broken or Risky Cryptographic Algorithm in the function mbedtls_mpi_exp_mod() in lignum.c in Mbed TLS Mbed TLS all versions before 3.0.0, 2.27.0 or 2.16.11 allows attackers with access to precise enough timing and memory access information (typically an untrusted operating system attacking a secure enclave such as SGX or the TrustZone secure world) to recover the private keys used in RSA.",
"evidence": "osv:DEBIAN-CVE-2021-36647",
"products": [
{
"name": {
"value": "mbedtls",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "2.16.11-0.1",
"evidence": "/affected/0/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "mbedtls",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "2.16.11-0.1",
"evidence": "/affected/1/ranges"
}
],
"affected_versions": []
},
{
"name": {
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"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
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"evidence": "/affected/2/ranges"
}
],
"affected_versions": []
}
],
"severity": "medium",
"structured": {
"id": "DEBIAN-CVE-2021-36647",
"aliases": [
"DEBIAN-CVE-2021-36647"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N"
}
],
"affected": [
{
"ranges": [
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"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
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}
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}
],
"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-2021-36647.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
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},
{
"fixed": "2.16.11-0.1"
}
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}
],
"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-2021-36647.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
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"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
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{
"fixed": "2.16.11-0.1"
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],
"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-2021-36647.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
],
"modified": "2026-10-23T18:05:22.893376793Z",
"provider": "osv",
"upstream": [
"CVE-2021-36647"
],
"references": [
"https://security-tracker.debian.org/tracker/CVE-2021-36647"
]
},
"related_cves": [
{
"value": "CVE-2021-36647",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 424352,
"published_at": "2023-01-17T21:15:10.88+00:00"
}