{"id":"DEBIAN-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":"2026-09-14T17:03:45.275309951Z","published":"2026-07-20T19:17:30.157Z","upstream":["CVE-2026-64194"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-64194"}],"affected":[{"package":{"name":"libnet-dns-perl","ecosystem":"Debian:12","purl":"pkg:deb/debian/libnet-dns-perl?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.36-1+deb12u1"}]}],"versions":["1.36-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-64194.json"}},{"package":{"name":"libnet-dns-perl","ecosystem":"Debian:13","purl":"pkg:deb/debian/libnet-dns-perl?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.56-0+deb13u1"}]}],"versions":["1.50-1","1.53-1","1.54-1","1.55-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-64194.json"}},{"package":{"name":"libnet-dns-perl","ecosystem":"Debian:14","purl":"pkg:deb/debian/libnet-dns-perl?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.56-1"}]}],"versions":["1.50-1","1.53-1","1.54-1","1.55-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-64194.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}