CVE-2026-64194 Affecting libnet-dns-perl package, versions <1.36-1+deb12u1


Severity

Recommended
low

Based on default assessment until relevant scores are available.

Threat Intelligence

EPSS
0.68% (51st percentile)

Do your applications use this vulnerable package?

In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.

Test your applications
  • Snyk IDSNYK-ECHOLATEST-LIBNETDNSPERL-18067180
  • published21 Jul 2026
  • disclosed20 Jul 2026

Introduced: 20 Jul 2026

CVE-2026-64194  (opens in a new tab)

How to fix?

Upgrade Echo:latest libnet-dns-perl to version 1.36-1+deb12u1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream libnet-dns-perl package and not the libnet-dns-perl package as distributed by Echo. See How to fix? for Echo:latest relevant fixed versions and status.

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 &lt; $offset prevents forward and circular chains, but still allows arbitrarily long backward chains. The per-offset cache ($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-&gt;new(\$wire) i.e. any point where the library decodes a DNS message from the network.

CVSS Base Scores

version 3.1