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": [
{
"extracted_events": [
{
"last_affected": "8.0"
}
],
"vendor_product": "redhat:enterprise_linux",
"cpes": [
"cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*"
],
"source": "CPE_FIELD"
}
]
}{
"cpe": "cpe:2.3:a:gnu:gnutls:*:*:*:*:*:*:*:*",
"extracted_events": [
{
"introduced": "0"
},
{
"fixed": "3.7.3"
}
],
"source": [
"CPE_FIELD",
"REFERENCES"
]
}"2026-05-18T22:23:55Z"
[
{
"target": {
"file": "lib/nettle/mac.c",
"function": "wrap_nettle_hash_fast"
},
"source": "https://gitlab.com/gnutls/gnutls@3db352734472d851318944db13be73da61300568",
"id": "CVE-2021-4209-1d4b3fe6",
"deprecated": false,
"signature_type": "Function",
"signature_version": "v1",
"digest": {
"length": 292.0,
"function_hash": "236935491575988941758897380685262140406"
}
},
{
"target": {
"file": "lib/nettle/mac.c"
},
"source": "https://gitlab.com/gnutls/gnutls@3db352734472d851318944db13be73da61300568",
"id": "CVE-2021-4209-d7f7968a",
"deprecated": false,
"signature_type": "Line",
"signature_version": "v1",
"digest": {
"line_hashes": [
"275608571458383794299871881526938393840",
"233275457814939103921727359368080843473",
"149924555111173732165894474521323559217",
"34228096393390421288319336369992983832"
],
"threshold": 0.9
}
}
]
"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2021-4209.json"