{"id":"CVE-2026-4438","title":"gethostbyaddr and gethostbyaddr_r return invalid DNS hostnames","summary":"Calling gethostbyaddr or gethostbyaddr_r with a configured nsswitch.conf that specifies the library's DNS backend in the GNU C library version 2.34 to version 2.43 could result in an invalid DNS hostname being returned to the caller in v…","severity":"medium","cvss":5.4,"cvssVector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N","cvssSource":"adp","cwe":["CWE-20"],"vendor":"The GNU C Library","product":"glibc","affected":["glibc >= 2.34 <= 2.43"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-03-23T15:06:13.636418Z"},"published":"2026-03-20","updated":"2026-10-15","sourceUpdated":"2026-10-15T01:12:10.681Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-4438","references":[{"url":"https://sourceware.org/bugzilla/show_bug.cgi?id=34015"}],"tags":["cve.org"],"epss":0.00316,"epssPercentile":0.22853,"ingestedAt":"2026-10-15T05:52:46.049Z","slug":"CVE-2026-4438","body":"## Overview\n\nCalling gethostbyaddr or gethostbyaddr_r with a configured nsswitch.conf that specifies the library's DNS backend in the GNU C library version 2.34 to version 2.43 could result in an invalid DNS hostname being returned to the caller in violation of the DNS specification.\n\n## Affected\n\n- `glibc >= 2.34 <= 2.43`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":29.7,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}