MediumFix available
gnutls28 — security advisory
A NULL pointer dereference flaw was found in GnuTLS. As Nettle's hash update functions internally call memcpy, providing zero-length input may cause undefined behavior. This flaw leads to a denial of service after authentication in rare circumstances.
- Products
- gnutls28
- Affected versions
- Not specified
- Fixed versions
- 3.7.3-2
- CVEs
- CVE-2021-4209
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 30 Oct 2026, 16:40 UTC · Revision 1
Source evidence
A NULL pointer dereference flaw was found in GnuTLS. As Nettle's hash update functions internally call memcpy, providing zero-length input may cause undefined behavior. This flaw leads to a denial of service after authentication in rare circumstances.
osv:DEBIAN-CVE-2021-4209
gnutls28
Fixed versions: 3.7.3-2
gnutls28
Fixed versions: 3.7.3-2
gnutls28
Fixed versions: 3.7.3-2
Complete source record
{
"id": "fcd285369af447ee8cf3abe1abaed26398a5fe0ddc992e085e0d9b2aa21fb66a",
"url": "https://osv.dev/vulnerability/DEBIAN-CVE-2021-4209",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "DEBIAN-CVE-2021-4209",
"summary": "A NULL pointer dereference flaw was found in GnuTLS. As Nettle's hash update functions internally call memcpy, providing zero-length input may cause undefined behavior. This flaw leads to a denial of service after authentication in rare circumstances.",
"evidence": "osv:DEBIAN-CVE-2021-4209",
"products": [
{
"name": {
"value": "gnutls28",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "3.7.3-2",
"evidence": "/affected/0/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "gnutls28",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "3.7.3-2",
"evidence": "/affected/1/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "gnutls28",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "3.7.3-2",
"evidence": "/affected/2/ranges"
}
],
"affected_versions": []
}
],
"severity": "medium",
"structured": {
"id": "DEBIAN-CVE-2021-4209",
"aliases": [
"DEBIAN-CVE-2021-4209"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "3.7.3-2"
}
]
}
],
"package": {
"name": "gnutls28",
"purl": "pkg:deb/debian/gnutls28?arch=source&distro=bookworm",
"ecosystem": "Debian:12"
},
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2021-4209.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "3.7.3-2"
}
]
}
],
"package": {
"name": "gnutls28",
"purl": "pkg:deb/debian/gnutls28?arch=source&distro=trixie",
"ecosystem": "Debian:13"
},
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2021-4209.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "3.7.3-2"
}
]
}
],
"package": {
"name": "gnutls28",
"purl": "pkg:deb/debian/gnutls28?arch=source&distro=forky",
"ecosystem": "Debian:14"
},
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2021-4209.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
],
"modified": "2026-10-15T09:47:36.379239138Z",
"provider": "osv",
"upstream": [
"CVE-2021-4209"
],
"references": [
"https://security-tracker.debian.org/tracker/CVE-2021-4209"
]
},
"related_cves": [
{
"value": "CVE-2021-4209",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 327915,
"published_at": "2022-08-24T16:15:09.927+00:00"
}