{"id":"AZL-87042","summary":"CVE-2026-42944 affecting package unbound for versions less than 1.25.1-1","details":"NLnet Labs Unbound 1.14.0 up to and including version 1.25.0 has a vulnerability that results in heap overflow when encoding multiple NSID and/or DNS Cookie EDNS and/or EDNS Padding options in the reply packet. The relevant options ('nsid', 'answer-cookie', 'pad-responses' (default)) need to be enabled for the vulnerability to be exploited. An adversary who can query Unbound can exploit the vulnerability by attaching multiple NSID and/or DNS Cookie EDNS and/or EDNS Padding options to the query. A flaw in the size calculation of the EDNS field truncates the correct value which allows the encoder to overflow the available space when writing. Those two combined lead to a heap overflow write of Unbound controlled data and eventually a crash. Unbound 1.25.1 contains a patch with a fix to de-duplicate the EDNS options and a fix to prevent truncation of the EDNS field size calculation.","modified":"2026-08-28T17:47:46.453929861Z","published":"2026-05-20T10:16:27Z","upstream":["CVE-2026-42944"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-42944"}],"affected":[{"package":{"name":"unbound","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/unbound"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.25.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-87042.json"}}],"schema_version":"1.9.0"}