{"id":"CVE-2026-42013","title":"A flaw was found in gnutls","summary":"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 …","severity":"high","cvss":8.2,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N","cwe":["CWE-295"],"published":"2026-05-26","updated":"2026-06-29","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-42013","references":[{"url":"https://access.redhat.com/errata/RHSA-2026:20611","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2026:20612","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2026:20613","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2026:26319","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2026:26409","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2026:29197","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2026:30004","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2026:30849","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2026:30850","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2026:32962","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/security/cve/CVE-2026-42013","label":"secalert@redhat.com"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2467448","label":"secalert@redhat.com"},{"url":"https://www.gnutls.org/security-new.html#GNUTLS-SA-2026-04-29-8","label":"secalert@redhat.com"}],"tags":["nvd"],"epss":0.00423,"epssPercentile":0.36216,"ingestedAt":"2026-06-29T13:42:11.959Z","slug":"CVE-2026-42013","body":"## Overview\n\nA 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":45,"depthScoreParts":{"impact":45.1,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}