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.
{
"unresolved_ranges": [
{
"cpe": "cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*",
"source": "CPE_FIELD",
"extracted_events": [
{
"last_affected": "8.0"
}
]
}
]
}"2026-04-12T02:01:35Z"
"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2021-4209.json"
[
{
"deprecated": false,
"signature_type": "Function",
"digest": {
"function_hash": "236935491575988941758897380685262140406",
"length": 292.0
},
"target": {
"file": "lib/nettle/mac.c",
"function": "wrap_nettle_hash_fast"
},
"source": "https://gitlab.com/gnutls/gnutls@3db352734472d851318944db13be73da61300568",
"signature_version": "v1",
"id": "CVE-2021-4209-1d4b3fe6"
},
{
"signature_type": "Line",
"deprecated": false,
"digest": {
"line_hashes": [
"275608571458383794299871881526938393840",
"233275457814939103921727359368080843473",
"149924555111173732165894474521323559217",
"34228096393390421288319336369992983832"
],
"threshold": 0.9
},
"target": {
"file": "lib/nettle/mac.c"
},
"source": "https://gitlab.com/gnutls/gnutls@3db352734472d851318944db13be73da61300568",
"signature_version": "v1",
"id": "CVE-2021-4209-d7f7968a"
}
]