CVE-2026-64194 Net::DNS versions through 1.55 for Perl allow Denial of Service via deep DNS compression pointer chains
Attackers can cause a denial of service in Perl applications using Net::DNS by sending crafted DNS packets with deep compression pointer chains.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-64194?
CVE-2026-64194 is a high-severity denial of service vulnerability in NLNETLABS Net::DNS, published on 20 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-674
Which versions are affected by CVE-2026-64194?
Linux distribution packages (13)
perl-Net-DNS SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | All versions | 1.14-150000.3.3.1 |
perl-Net-DNS SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | All versions | 1.14-150000.3.3.1 |
perl-Net-DNS SUSE:Linux Enterprise High Performance Computing 15 SP5-ESPOS | All versions | 1.14-150000.3.3.1 |
perl-Net-DNS SUSE:Linux Enterprise High Performance Computing 15 SP5-LTSS | All versions | 1.14-150000.3.3.1 |
perl-Net-DNS SUSE:Linux Enterprise Module for Basesystem 15 SP7 | All versions | 1.14-150000.3.3.1 |
perl-Net-DNS SUSE:Linux Enterprise Server 12 SP5-LTSS | All versions | 0.73-5.3.1 |
perl-Net-DNS SUSE:Linux Enterprise Server 15 SP4-LTSS | All versions | 1.14-150000.3.3.1 |
perl-Net-DNS SUSE:Linux Enterprise Server 15 SP5-LTSS | All versions | 1.14-150000.3.3.1 |
perl-Net-DNS SUSE:Linux Enterprise Server 15 SP6-LTSS | All versions | 1.14-150000.3.3.1 |
perl-Net-DNS SUSE:Linux Enterprise Server LTSS Extended Security 12 SP5 | All versions | 0.73-5.3.1 |
perl-Net-DNS SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | All versions | 1.14-150000.3.3.1 |
perl-Net-DNS SUSE:Linux Enterprise Server for SAP Applications 15 SP5 | All versions | 1.14-150000.3.3.1 |
perl-Net-DNS SUSE:Linux Enterprise Server for SAP Applications 15 SP6 | All versions | 1.14-150000.3.3.1 |
How do I fix CVE-2026-64194?
Upgrade to a fixed version.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-64194 being exploited?
There is no known exploitation of CVE-2026-64194 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-64194, GHSA-m3gj-74x3-vc94, SUSE-SU-2026:3431-1, SUSE-SU-2026:3456-1, UBUNTU-CVE-2026-64194.