{"id":"UBUNTU-CVE-2026-42012","details":"A flaw was found in gnutls. A remote attacker could exploit this vulnerability by presenting a specially crafted certificate that contains Uniform Resource Identifier (URI) or Service (SRV) Subject Alternative Names (SANs). This could cause the certificate validation process to incorrectly fall back to checking DNS hostnames against the Common Name (CN), potentially allowing the attacker to spoof legitimate services or intercept sensitive information.","modified":"2026-07-14T23:44:43.007167926Z","published":"2026-04-30T00:00:00Z","related":["USN-8284-1","USN-8539-1"],"upstream":["CVE-2026-42012"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-42012"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-42012"},{"type":"REPORT","url":"https://www.gnutls.org/security-new.html#GNUTLS-SA-2026-04-29-7"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-8284-1"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-8539-1"}],"affected":[{"package":{"name":"gnutls28","ecosystem":"Ubuntu:Pro:16.04:LTS","purl":"pkg:deb/ubuntu/gnutls28?arch=source&distro=esm-infra-legacy%2Fxenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.4.10-4ubuntu1.9+esm4"}]}],"versions":["3.3.15-5ubuntu2","3.3.18-1ubuntu1","3.3.20-1ubuntu1","3.4.9-2ubuntu1","3.4.10-4ubuntu1","3.4.10-4ubuntu1.1","3.4.10-4ubuntu1.2","3.4.10-4ubuntu1.3","3.4.10-4ubuntu1.4","3.4.10-4ubuntu1.5","3.4.10-4ubuntu1.6","3.4.10-4ubuntu1.7","3.4.10-4ubuntu1.8","3.4.10-4ubuntu1.9","3.4.10-4ubuntu1.9+esm1","3.4.10-4ubuntu1.9+esm2","3.4.10-4ubuntu1.9+esm3"],"ecosystem_specific":{"binaries":[{"binary_version":"3.4.10-4ubuntu1.9+esm4","binary_name":"gnutls-bin"},{"binary_name":"guile-gnutls","binary_version":"3.4.10-4ubuntu1.9+esm4"},{"binary_name":"libgnutls-openssl27","binary_version":"3.4.10-4ubuntu1.9+esm4"},{"binary_name":"libgnutls30","binary_version":"3.4.10-4ubuntu1.9+esm4"},{"binary_version":"3.4.10-4ubuntu1.9+esm4","binary_name":"libgnutlsxx28"}],"availability":"Available with Ubuntu Pro with Legacy support add-on: https://ubuntu.com/pro"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-42012.json"}},{"package":{"name":"gnutls28","ecosystem":"Ubuntu:Pro:18.04:LTS","purl":"pkg:deb/ubuntu/gnutls28?arch=source&distro=esm-infra%2Fbionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.5.18-1ubuntu1.6+esm4"}]}],"versions":["3.5.8-6ubuntu3","3.5.17-1ubuntu1","3.5.17-1ubuntu3","3.5.18-1ubuntu1","3.5.18-1ubuntu1.1","3.5.18-1ubuntu1.2","3.5.18-1ubuntu1.3","3.5.18-1ubuntu1.4","3.5.18-1ubuntu1.5","3.5.18-1ubuntu1.6","3.5.18-1ubuntu1.6+esm1","3.5.18-1ubuntu1.6+esm2","3.5.18-1ubuntu1.6+esm3"],"ecosystem_specific":{"binaries":[{"binary_name":"gnutls-bin","binary_version":"3.5.18-1ubuntu1.6+esm4"},{"binary_name":"libgnutls-dane0","binary_version":"3.5.18-1ubuntu1.6+esm4"},{"binary_name":"libgnutls-openssl27","binary_version":"3.5.18-1ubuntu1.6+esm4"},{"binary_name":"libgnutls30","binary_version":"3.5.18-1ubuntu1.6+esm4"},{"binary_version":"3.5.18-1ubuntu1.6+esm4","binary_name":"libgnutlsxx28"}],"availability":"Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-42012.json"}},{"package":{"name":"gnutls28","ecosystem":"Ubuntu:Pro:20.04:LTS","purl":"pkg:deb/ubuntu/gnutls28?arch=source&distro=esm-infra%2Ffocal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.6.13-2ubuntu1.12+esm3"}]}],"versions":["3.6.9-5ubuntu1","3.6.9-5ubuntu2","3.6.10-5","3.6.11.1-2","3.6.11.1-2ubuntu2","3.6.13-2ubuntu1","3.6.13-2ubuntu1.1","3.6.13-2ubuntu1.2","3.6.13-2ubuntu1.3","3.6.13-2ubuntu1.6","3.6.13-2ubuntu1.7","3.6.13-2ubuntu1.8","3.6.13-2ubuntu1.9","3.6.13-2ubuntu1.10","3.6.13-2ubuntu1.11","3.6.13-2ubuntu1.12","3.6.13-2ubuntu1.12+esm1","3.6.13-2ubuntu1.12+esm2"],"ecosystem_specific":{"binaries":[{"binary_name":"gnutls-bin","binary_version":"3.6.13-2ubuntu1.12+esm3"},{"binary_version":"3.6.13-2ubuntu1.12+esm3","binary_name":"guile-gnutls"},{"binary_name":"libgnutls-dane0","binary_version":"3.6.13-2ubuntu1.12+esm3"},{"binary_version":"3.6.13-2ubuntu1.12+esm3","binary_name":"libgnutls-openssl27"},{"binary_version":"3.6.13-2ubuntu1.12+esm3","binary_name":"libgnutls30"},{"binary_name":"libgnutlsxx28","binary_version":"3.6.13-2ubuntu1.12+esm3"}],"availability":"Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-42012.json"}},{"package":{"name":"gnutls28","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/gnutls28?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.7.3-4ubuntu1.9"}]}],"versions":["3.7.1-5ubuntu1","3.7.2-2ubuntu1","3.7.2-4ubuntu1","3.7.2-5ubuntu1","3.7.3-4ubuntu1","3.7.3-4ubuntu1.1","3.7.3-4ubuntu1.2","3.7.3-4ubuntu1.3","3.7.3-4ubuntu1.4","3.7.3-4ubuntu1.5","3.7.3-4ubuntu1.6","3.7.3-4ubuntu1.7","3.7.3-4ubuntu1.8"],"ecosystem_specific":{"binaries":[{"binary_name":"gnutls-bin","binary_version":"3.7.3-4ubuntu1.9"},{"binary_name":"guile-gnutls","binary_version":"3.7.3-4ubuntu1.9"},{"binary_name":"libgnutls-dane0","binary_version":"3.7.3-4ubuntu1.9"},{"binary_name":"libgnutls-openssl27","binary_version":"3.7.3-4ubuntu1.9"},{"binary_version":"3.7.3-4ubuntu1.9","binary_name":"libgnutls30"},{"binary_version":"3.7.3-4ubuntu1.9","binary_name":"libgnutlsxx28"}],"availability":"No subscription required"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-42012.json"}},{"package":{"name":"gnutls28","ecosystem":"Ubuntu:Pro:FIPS-preview:22.04:LTS","purl":"pkg:deb/ubuntu/gnutls28?arch=source&distro=fips-preview%2Fjammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.7.3-4ubuntu1.2+Fips1.1"],"ecosystem_specific":{"binaries":[{"binary_name":"gnutls-bin","binary_version":"3.7.3-4ubuntu1.2+Fips1.1"},{"binary_name":"guile-gnutls","binary_version":"3.7.3-4ubuntu1.2+Fips1.1"},{"binary_name":"libgnutls-dane0","binary_version":"3.7.3-4ubuntu1.2+Fips1.1"},{"binary_version":"3.7.3-4ubuntu1.2+Fips1.1","binary_name":"libgnutls-openssl27"},{"binary_name":"libgnutls30","binary_version":"3.7.3-4ubuntu1.2+Fips1.1"},{"binary_name":"libgnutlsxx28","binary_version":"3.7.3-4ubuntu1.2+Fips1.1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-42012.json"}},{"package":{"name":"gnutls28","ecosystem":"Ubuntu:Pro:FIPS-updates:22.04:LTS","purl":"pkg:deb/ubuntu/gnutls28?arch=source&distro=fips-updates%2Fjammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.7.3-4ubuntu1.9+Fips1"}]}],"versions":["3.7.3-4ubuntu1.2+Fips1.1","3.7.3-4ubuntu1.3+Fips1.1","3.7.3-4ubuntu1.4+Fips1","3.7.3-4ubuntu1.5+Fips1","3.7.3-4ubuntu1.6+Fips1","3.7.3-4ubuntu1.7+Fips1","3.7.3-4ubuntu1.7+Fips1.1","3.7.3-4ubuntu1.8+Fips1.1"],"ecosystem_specific":{"binaries":[{"binary_version":"3.7.3-4ubuntu1.9+Fips1","binary_name":"gnutls-bin"},{"binary_name":"guile-gnutls","binary_version":"3.7.3-4ubuntu1.9+Fips1"},{"binary_version":"3.7.3-4ubuntu1.9+Fips1","binary_name":"libgnutls-dane0"},{"binary_version":"3.7.3-4ubuntu1.9+Fips1","binary_name":"libgnutls-openssl27"},{"binary_name":"libgnutls30","binary_version":"3.7.3-4ubuntu1.9+Fips1"},{"binary_version":"3.7.3-4ubuntu1.9+Fips1","binary_name":"libgnutlsxx28"}],"availability":"Available with Ubuntu Pro: https://ubuntu.com/pro"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-42012.json"}},{"package":{"name":"gnutls28","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/gnutls28?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.8.3-1.1ubuntu3.6"}]}],"versions":["3.8.1-4ubuntu1","3.8.1-4ubuntu6","3.8.1-4ubuntu7","3.8.3-1ubuntu1","3.8.3-1.1ubuntu2","3.8.3-1.1ubuntu3","3.8.3-1.1ubuntu3.1","3.8.3-1.1ubuntu3.2","3.8.3-1.1ubuntu3.3","3.8.3-1.1ubuntu3.4","3.8.3-1.1ubuntu3.5"],"ecosystem_specific":{"binaries":[{"binary_name":"gnutls-bin","binary_version":"3.8.3-1.1ubuntu3.6"},{"binary_name":"libgnutls-dane0t64","binary_version":"3.8.3-1.1ubuntu3.6"},{"binary_name":"libgnutls-openssl27t64","binary_version":"3.8.3-1.1ubuntu3.6"},{"binary_name":"libgnutls30t64","binary_version":"3.8.3-1.1ubuntu3.6"}],"availability":"No subscription required"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-42012.json"}},{"package":{"name":"gnutls28","ecosystem":"Ubuntu:Pro:FIPS-updates:24.04:LTS","purl":"pkg:deb/ubuntu/gnutls28?arch=source&distro=fips-updates%2Fnoble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.8.3-1.1ubuntu3.6+Fips1.2"}]}],"versions":["3.8.3-1.1ubuntu3.1+Fips1","3.8.3-1.1ubuntu3.4+Fips1","3.8.3-1.1ubuntu3.4+Fips1.1","3.8.3-1.1ubuntu3.5+Fips1.1"],"ecosystem_specific":{"binaries":[{"binary_name":"gnutls-bin","binary_version":"3.8.3-1.1ubuntu3.6+Fips1.2"},{"binary_name":"libgnutls-dane0t64","binary_version":"3.8.3-1.1ubuntu3.6+Fips1.2"},{"binary_name":"libgnutls-openssl27t64","binary_version":"3.8.3-1.1ubuntu3.6+Fips1.2"},{"binary_version":"3.8.3-1.1ubuntu3.6+Fips1.2","binary_name":"libgnutls30t64"}],"availability":"Available with Ubuntu Pro: https://ubuntu.com/pro"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-42012.json"}},{"package":{"name":"gnutls28","ecosystem":"Ubuntu:25.10","purl":"pkg:deb/ubuntu/gnutls28?arch=source&distro=questing"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.8.9-3ubuntu2.2"}]}],"versions":["3.8.9-2ubuntu3","3.8.9-3ubuntu1","3.8.9-3ubuntu2","3.8.9-3ubuntu2.1"],"ecosystem_specific":{"availability":"No subscription required","binaries":[{"binary_name":"gnutls-bin","binary_version":"3.8.9-3ubuntu2.2"},{"binary_version":"3.8.9-3ubuntu2.2","binary_name":"libgnutls-dane0t64"},{"binary_name":"libgnutls-openssl27t64","binary_version":"3.8.9-3ubuntu2.2"},{"binary_name":"libgnutls30t64","binary_version":"3.8.9-3ubuntu2.2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-42012.json"}},{"package":{"name":"gnutls28","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/gnutls28?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.8.12-2ubuntu1.1"}]}],"versions":["3.8.9-3ubuntu2","3.8.10-3ubuntu1","3.8.12-2ubuntu1"],"ecosystem_specific":{"binaries":[{"binary_name":"gnutls-bin","binary_version":"3.8.12-2ubuntu1.1"},{"binary_version":"3.8.12-2ubuntu1.1","binary_name":"libgnutls-dane0t64"},{"binary_version":"3.8.12-2ubuntu1.1","binary_name":"libgnutls-openssl27t64"},{"binary_name":"libgnutls30t64","binary_version":"3.8.12-2ubuntu1.1"}],"availability":"No subscription required"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-42012.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:H/A:N"},{"type":"Ubuntu","score":"medium"}]}