{"id":"CVE-2021-4209","title":"A NULL pointer dereference flaw was found in GnuTLS","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 …","severity":"medium","cvss":6.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","cwe":["CWE-476","CWE-476"],"vendor":"gnu","product":"gnutls","affected":["gnutls < 3.7.3","enterprise_linux = 8.0","active_iq_unified_manager","solidfire_&_hci_management_node","hci_bootstrap_os"],"patched":["gnutls 3.7.3"],"published":"2022-08-24","updated":"2026-10-14","sourceUpdated":"2026-10-14T11:16:55.207","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2021-4209","references":[{"url":"https://access.redhat.com/security/cve/CVE-2021-4209","label":"secalert@redhat.com"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2044156","label":"secalert@redhat.com"},{"url":"https://gitlab.com/gnutls/gnutls/-/commit/3db352734472d851318944db13be73da61300568","label":"secalert@redhat.com"},{"url":"https://gitlab.com/gnutls/gnutls/-/issues/1306","label":"secalert@redhat.com"},{"url":"https://gitlab.com/gnutls/gnutls/-/merge_requests/1503","label":"secalert@redhat.com"},{"url":"https://security.netapp.com/advisory/ntap-20220915-0005/","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/security/cve/CVE-2021-4209","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2044156","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://gitlab.com/gnutls/gnutls/-/commit/3db352734472d851318944db13be73da61300568","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://gitlab.com/gnutls/gnutls/-/issues/1306","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://gitlab.com/gnutls/gnutls/-/merge_requests/1503","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://security.netapp.com/advisory/ntap-20220915-0005/","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-398330.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"}],"tags":["nvd"],"epss":0.01748,"epssPercentile":0.77253,"ingestedAt":"2026-10-14T11:27:22.129Z","slug":"CVE-2021-4209","body":"## Overview\n\nA 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.\n\n## Affected\n\n- `gnutls < 3.7.3`\n- `enterprise_linux = 8.0`\n- `active_iq_unified_manager`\n- `solidfire_&_hci_management_node`\n- `hci_bootstrap_os`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `gnutls 3.7.3`","depth":"sunlit","depthScore":36,"depthScoreParts":{"impact":35.8,"likelihood":0.3,"exploitation":0,"ransomware":0},"changes":[]}