{"id":"CVE-2026-42013","summary":"Gnutls: gnutls: certificate validation bypass due to oversized subject alternative name","details":"A flaw was found in gnutls. When validating certificates, an oversized Subject Alternative Name (SAN) could cause the validation process to incorrectly fall back to checking the Common Name (CN) field. This could allow a remote attacker to bypass proper certificate validation, potentially leading to spoofing or man-in-the-middle attacks.","modified":"2026-10-02T11:45:38.818779078Z","published":"2026-05-26T21:29:32.887Z","related":["SUSE-SU-2026:2087-1","SUSE-SU-2026:2115-1","SUSE-SU-2026:21752-1","SUSE-SU-2026:21784-1","SUSE-SU-2026:21815-1","SUSE-SU-2026:21867-1","SUSE-SU-2026:2822-1","SUSE-SU-2026:2923-1","SUSE-SU-2026:2924-1","openSUSE-SU-2026:10691-1","openSUSE-SU-2026:20778-1"],"database_specific":{"cwe_ids":["CWE-295"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42013.json","cna_assigner":"redhat"},"references":[{"type":"WEB","url":"https://access.redhat.com/downloads/content/package-browser/"},{"type":"WEB","url":"https://catalog.redhat.com/software/containers/"},{"type":"WEB","url":"https://www.gnutls.org/security-new.html#GNUTLS-SA-2026-04-29-8"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:13274"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:20611"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:20612"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:20613"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:26319"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:26409"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:29197"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:30004"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:30849"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:30850"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:32962"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:33125"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:40762"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:41921"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:43575"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:56853"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:57483"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:58981"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:59831"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:60019"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:72502"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:74674"},{"type":"ADVISORY","url":"https://access.redhat.com/security/cve/CVE-2026-42013"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42013.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-42013"},{"type":"REPORT","url":"https://bugzilla.redhat.com/show_bug.cgi?id=2467448"},{"type":"PACKAGE","url":"https://gitlab.com/gnutls/gnutls"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://gitlab.com/gnutls/gnutls","events":[{"introduced":"0"},{"last_affected":"0"}],"database_specific":{"source":"AFFECTED_FIELD","extracted_events":[{"introduced":"0"},{"last_affected":"0"}]}}],"versions":["0"],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-42013.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N"}]}