{"id":"CVE-2026-64194","title":"Net::DNS versions through 1.55 for Perl allow Denial of Service via deep DNS compression pointer chains.\n\nNet::DNS::DomainName::decode follows RFC 1035 compression pointers by recursing into itself with no depth limit","summary":"Net::DNS versions through 1.55 for Perl allow Denial of Service via deep DNS compression pointer chains.\n\nNet::DNS::DomainName::decode follows RFC 1035 compression pointers by recursing into itself with no depth limit. It is possible to …","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cwe":["CWE-674"],"published":"2026-07-20","updated":"2026-08-30","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-64194","references":[{"url":"https://metacpan.org/release/NLNETLABS/Net-DNS-1.55_01/changes","label":"9b29abf9-4ab0-4765-b253-1875cd9b441e"},{"url":"https://rt.cpan.org/Ticket/Display.html?id=179946","label":"9b29abf9-4ab0-4765-b253-1875cd9b441e"},{"url":"https://www.net-dns.org/blog/#release-candidate-for-netdns-1.56","label":"9b29abf9-4ab0-4765-b253-1875cd9b441e"},{"url":"http://www.openwall.com/lists/oss-security/2026/07/20/13","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.debian.org/debian-lts-announce/2026/08/msg00052.html","label":"af854a3a-2127-422b-91ae-364da2661108"}],"tags":["nvd"],"epss":0.00416,"epssPercentile":0.3563,"ingestedAt":"2026-08-30T21:58:10.818Z","slug":"CVE-2026-64194","body":"## Overview\n\nNet::DNS versions through 1.55 for Perl allow Denial of Service via deep DNS compression pointer chains.\n\nNet::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.\n\nThe guard `$link < $offset` prevents forward and circular chains, but still allows arbitrarily long backward chains. The per-offset cache (`$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.\n\nA 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.\n\nThe vulnerability is triggered by `Net::DNS::Packet->new(\\$wire)` i.e. any point where the library decodes a DNS message from the network.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}