libnet-dns-perl — security advisory
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 < $offset` prevents forward and circular chains, but still allows arbitrarily long backward chains. The per-offset cache (`$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->new(\$wire)` i.e. any point where the library decodes a DNS message from the network.
- Products
- libnet-dns-perl
- Affected versions
- 0.68-1.2, 0.68-1.2build1, 0.81-2, 0.81-2build1, 1.10-2, 1.20-1, 1.21-1, 1.22-1, 1.29-1, 1.32-1, 1.33-1, 1.39-2ubuntu1, 1.40-1ubuntu1, 1.44-1ubuntu1, 1.50-1ubuntu1, 1.53-1ubuntu1, 1.54-1ubuntu1, 1.55-1ubuntu1
- Fixed versions
- Not specified
- CVEs
- CVE-2026-64194
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 02:49 UTC · Revision 1
Source evidence
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 < $offset` prevents forward and circular chains, but still allows arbitrarily long backward chains. The per-offset cache (`$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->new(\$wire)` i.e. any point where the library decodes a DNS message from the network.
osv:UBUNTU-CVE-2026-64194
libnet-dns-perl
Fixed versions: Not specified
libnet-dns-perl
Fixed versions: Not specified
libnet-dns-perl
Fixed versions: Not specified
libnet-dns-perl
Fixed versions: Not specified
libnet-dns-perl
Fixed versions: Not specified
libnet-dns-perl
Fixed versions: Not specified
libnet-dns-perl
Fixed versions: Not specified
libnet-dns-perl
Fixed versions: Not specified
Complete source record
{
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"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-64194",
"method": "structured",
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"summary": "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 < $offset` prevents forward and circular chains, but still allows arbitrarily long backward chains. The per-offset cache (`$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->new(\\$wire)` i.e. any point where the library decodes a DNS message from the network.",
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"modified": "2026-10-17T12:59:16.136263036Z",
"provider": "osv",
"upstream": [
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"references": [
"https://ubuntu.com/security/CVE-2026-64194",
"https://www.cve.org/CVERecord?id=CVE-2026-64194",
"https://lists.security.metacpan.org/cve-announce/msg/41989541/",
"https://rt.cpan.org/Ticket/Display.html?id=179946"
]
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"source_id": "core-osv",
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"published_at": "2026-07-20T19:17:00+00:00"
}