{"id":"CVE-2026-64194","state":"PUBLISHED","title":"Net::DNS versions through 1.55 for Perl allow Denial of Service via deep DNS compression pointer chains","description":"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 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.","publishedAt":"2026-07-20T17:55:05.169Z","updatedAt":"2026-08-30T20:06:49.756Z","severity":{"score":7.5,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"CISA-ADP"},"assigner":"CPANSec","products":["NLNETLABS Net::DNS"],"affected":[{"vendor":"NLNETLABS","product":"Net::DNS","packageName":"Net-DNS","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThanOrEqual":"1.55","versionType":"custom"}],"collectionURL":"https://cpan.org/modules","programFiles":["lib/Net/DNS/DomainName.pm"],"programRoutines":[{"name":"Net::DNS::DomainName::decode"}],"repo":"https://www.net-dns.org/svn/net-dns/"}],"references":["https://www.net-dns.org/blog/#release-candidate-for-netdns-1.56","https://rt.cpan.org/Ticket/Display.html?id=179946","https://metacpan.org/release/NLNETLABS/Net-DNS-1.55_01/changes","http://www.openwall.com/lists/oss-security/2026/07/20/13","https://lists.debian.org/debian-lts-announce/2026/08/msg00052.html"],"weaknesses":["CWE-674"],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/64xxx/CVE-2026-64194.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-64194","state":"PUBLISHED","datePublished":"2026-07-20T17:55:05.169Z","dateUpdated":"2026-08-30T20:06:49.756Z","assignerShortName":"CPANSec","assignerOrgId":"9b29abf9-4ab0-4765-b253-1875cd9b441e","dateReserved":"2026-07-19T10:13:00.756Z"},"containers":{"cna":{"title":"Net::DNS versions through 1.55 for Perl allow Denial of Service via deep DNS compression pointer chains","descriptions":[{"lang":"en","value":"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 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."}],"affected":[{"vendor":"NLNETLABS","product":"Net::DNS","packageName":"Net-DNS","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThanOrEqual":"1.55","versionType":"custom"}],"collectionURL":"https://cpan.org/modules","programFiles":["lib/Net/DNS/DomainName.pm"],"programRoutines":[{"name":"Net::DNS::DomainName::decode"}],"repo":"https://www.net-dns.org/svn/net-dns/"}],"references":[{"url":"https://www.net-dns.org/blog/#release-candidate-for-netdns-1.56"},{"url":"https://rt.cpan.org/Ticket/Display.html?id=179946","tags":["issue-tracking"]},{"url":"https://metacpan.org/release/NLNETLABS/Net-DNS-1.55_01/changes","tags":["release-notes"]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-674","description":"CWE-674 Uncontrolled Recursion","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"CPANSec","orgId":"9b29abf9-4ab0-4765-b253-1875cd9b441e","dateUpdated":"2026-07-20T17:55:05.169Z"},"credits":[{"lang":"en","type":"reporter","value":"Steffen Ullrich"}],"solutions":[{"lang":"en","value":"Upgrade to version 1.56 or later."}],"source":{"discovery":"UNKNOWN"},"timeline":[{"lang":"en","time":"2026-07-10T00:00:00.000Z","value":"Issue reported publicly via RT."},{"lang":"en","time":"2026-07-10T00:00:00.000Z","value":"Version 1.55_01 (release candidate for version 1.56) published on CPAN."},{"lang":"en","time":"2026-07-18T00:00:00.000Z","value":"Version 1.56 published on CPAN."}],"x_generator":{"engine":"cpansec-cna-tool 0.1"}},"adp":[{"title":"CVE Program Container","references":[{"url":"http://www.openwall.com/lists/oss-security/2026/07/20/13"},{"url":"https://lists.debian.org/debian-lts-announce/2026/08/msg00052.html"}],"providerMetadata":{"shortName":"CVE","orgId":"af854a3a-2127-422b-91ae-364da2661108","dateUpdated":"2026-08-30T20:06:49.756Z"}},{"title":"CISA ADP Vulnrichment","metrics":[{"cvssV3_1":{"scope":"UNCHANGED","version":"3.1","baseScore":7.5,"attackVector":"NETWORK","baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","integrityImpact":"NONE","userInteraction":"NONE","attackComplexity":"LOW","availabilityImpact":"HIGH","privilegesRequired":"NONE","confidentialityImpact":"NONE"}},{"other":{"type":"ssvc","content":{"timestamp":"2026-07-21T18:55:36.580996Z","id":"CVE-2026-64194","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-07-21T18:56:01.149Z"}}]}}}