{"id":"UBUNTU-CVE-2026-64194","details":"Net::DNS versions through 1.55 for Perl allow Denial of Service via deep DNS compression pointer chains. Net::DNS::DomainName::decode follows RFC 1035 compression pointers by recursing into itself with no depth limit. It is possible to construct a name which saturates the call stack (at least with larger TCP responses), leading to a potential Denial of Service. The guard `$link \u003c $offset` prevents forward and circular chains, but still allows arbitrarily long backward chains. The per-offset cache (`$cache`) is populated at the start of each call and short-circuits only re-traverses of the same offset - the initial descent through a fresh chain still recurses at full depth. A crafted packet can chain two-byte compression pointers so that each one points two bytes earlier than the previous, producing a chain length of `offset / 2`. For the 14-bit pointer field (max offset 16383) this gives up to ~8191 recursive frames. For a TCP DNS message the limit is the 16-bit length field (~32767 frames). Perl's default C stack handles only a few thousand frames; beyond that the process receives SIGSEGV or similar, which is a denial-of-service for any application parsing untrusted DNS data. The vulnerability is triggered by `Net::DNS::Packet-\u003enew(\\$wire)` i.e. any point where the library decodes a DNS message from the network.","modified":"2026-07-29T10:18:53.022903447Z","published":"2026-07-20T19:17:00Z","upstream":["CVE-2026-64194"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-64194"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-64194"},{"type":"REPORT","url":"https://lists.security.metacpan.org/cve-announce/msg/41989541/"},{"type":"REPORT","url":"https://rt.cpan.org/Ticket/Display.html?id=179946"}],"affected":[{"package":{"name":"libnet-dns-perl","ecosystem":"Ubuntu:14.04:LTS","purl":"pkg:deb/ubuntu/libnet-dns-perl?arch=source&distro=trusty"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.68-1.2","0.68-1.2build1"],"ecosystem_specific":{"binaries":[{"binary_name":"libnet-dns-perl","binary_version":"0.68-1.2build1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-64194.json"}},{"package":{"name":"libnet-dns-perl","ecosystem":"Ubuntu:16.04:LTS","purl":"pkg:deb/ubuntu/libnet-dns-perl?arch=source&distro=xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.81-2","0.81-2build1"],"ecosystem_specific":{"binaries":[{"binary_version":"0.81-2build1","binary_name":"libnet-dns-perl"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-64194.json"}},{"package":{"name":"libnet-dns-perl","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/libnet-dns-perl?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.10-2"],"ecosystem_specific":{"binaries":[{"binary_version":"1.10-2","binary_name":"libnet-dns-perl"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-64194.json"}},{"package":{"name":"libnet-dns-perl","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/libnet-dns-perl?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.20-1","1.21-1","1.22-1"],"ecosystem_specific":{"binaries":[{"binary_version":"1.22-1","binary_name":"libnet-dns-perl"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-64194.json"}},{"package":{"name":"libnet-dns-perl","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/libnet-dns-perl?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.29-1","1.32-1","1.33-1"],"ecosystem_specific":{"binaries":[{"binary_name":"libnet-dns-perl","binary_version":"1.33-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-64194.json"}},{"package":{"name":"libnet-dns-perl","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/libnet-dns-perl?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.39-2ubuntu1","1.40-1ubuntu1","1.44-1ubuntu1"],"ecosystem_specific":{"binaries":[{"binary_name":"libnet-dns-perl","binary_version":"1.44-1ubuntu1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-64194.json"}},{"package":{"name":"libnet-dns-perl","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/libnet-dns-perl?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.50-1ubuntu1","1.53-1ubuntu1","1.54-1ubuntu1"],"ecosystem_specific":{"binaries":[{"binary_version":"1.54-1ubuntu1","binary_name":"libnet-dns-perl"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-64194.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},{"type":"Ubuntu","score":"medium"}]}