Affected: AlmaLinux:9: perl-Net-DNS, AlmaLinux:9: perl-Net-DNS-Nameserver

The perl-Net-DNS package contains a collection of Perl modules that act as a Domain Name System (DNS) resolver. It allows the programmer to perform DNS queries that are beyond the capabilities of the gethostbyname and gethostbyaddr routines.

Security Fix(es):

* perl-Net-DNS: Net::DNS: Denial of Service via unbounded recursion with misplaced TSIG records (CVE-2026-81928)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Affected: Homebrew: fpdns

Net::DNS versions before 1.57 for Perl allow memory exhaustion via unbounded recursion in sig_data when re-encoding a message with a misplaced TSIG record.

sig_data signs a message by re-encoding it, and removes TSIG records only from the additional section. A TSIG decoded into the answer or authority section survives that step and is signed again, so encoding re-enters sig_data with no termination condition. Decoding does not reject such a message: a TSIG that is not the last record on the wire raises "misplaced or corrupt TSIG", but the error is caught, reported as a warning, and the record is left in the packet. RFC 8945 section 5.2 requires the message to be dropped.

The recursion is reached only when the decoded TSIG carries an empty MAC, since a MAC recovered from the wire short-circuits the signing step. It is reached only from code that re-encodes a message it decoded, such as a forwarder or a proxy. A decoded message that is never re-encoded is unaffected. Message direction does not matter: a query reaches the same path as a response.

Each cycle re-encodes the whole message, so fewer than 100 bytes on the wire exhaust available memory and terminate the process.

Net::DNS versions before 1.57 for Perl allow memory exhaustion via unbounded recursion in sig_data when re-encoding a message with a misplaced TSIG record.

sig_data signs a message by re-encoding it, and removes TSIG records only from the additional section. A TSIG decoded into the answer or authority section survives that step and is signed again, so encoding re-enters sig_data with no termination condition. Decoding does not reject such a message: a TSIG that is not the last record on the wire raises "misplaced or corrupt TSIG", but the error is caught, reported as a warning, and the record is left in the packet. RFC 8945 section 5.2 requires the message to be dropped.

The recursion is reached only when the decoded TSIG carries an empty MAC, since a MAC recovered from the wire short-circuits the signing step. It is reached only from code that re-encodes a message it decoded, such as a forwarder or a proxy. A decoded message that is never re-encoded is unaffected. Message direction does not matter: a query reaches the same path as a response.

Each cycle re-encodes the whole message, so fewer than 100 bytes on the wire exhaust available memory and terminate the process.

Net::DNS versions before 1.57 for Perl allow memory exhaustion via unbounded recursion in sig_data when re-encoding a message with a misplaced TSIG record.

sig_data signs a message by re-encoding it, and removes TSIG records only from the additional section. A TSIG decoded into the answer or authority section survives that step and is signed again, so encoding re-enters sig_data with no termination condition. Decoding does not reject such a message: a TSIG that is not the last record on the wire raises "misplaced or corrupt TSIG", but the error is caught, reported as a warning, and the record is left in the packet. RFC 8945 section 5.2 requires the message to be dropped.

The recursion is reached only when the decoded TSIG carries an empty MAC, since a MAC recovered from the wire short-circuits the signing step. It is reached only from code that re-encodes a message it decoded, such as a forwarder or a proxy. A decoded message that is never re-encoded is unaffected. Message direction does not matter: a query reaches the same path as a response.

Each cycle re-encodes the whole message, so fewer than 100 bytes on the wire exhaust available memory and terminate the process.

perl-Net-DNS-1.570.0-1.1 on GA media

Affected: Rocky Linux:9: perl-Net-DNS

The perl-Net-DNS package contains a collection of Perl modules that act as a Domain Name System (DNS) resolver. It allows the programmer to perform DNS queries that are beyond the capabilities of the gethostbyname and gethostbyaddr routines.

Security Fix(es):

* perl-Net-DNS: Net::DNS: Denial of Service via unbounded recursion with misplaced TSIG records (CVE-2026-81928)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Security update for perl-Net-DNS

Affected: Ubuntu:14.04:LTS: libnet-dns-perl, Ubuntu:16.04:LTS: libnet-dns-perl, Ubuntu:18.04:LTS: libnet-dns-perl, Ubuntu:20.04:LTS: libnet-dns-perl, Ubuntu:22.04:LTS: libnet-dns-perl, Ubuntu:24.04:LTS: libnet-dns-perl, Ubuntu:26.04:LTS: libnet-dns-perl

Net::DNS versions before 1.57 for Perl allow memory exhaustion via unbounded recursion in sig_data when re-encoding a message with a misplaced TSIG record. sig_data signs a message by re-encoding it, and removes TSIG records only from the additional section. A TSIG decoded into the answer or authority section survives that step and is signed again, so encoding re-enters sig_data with no termination condition. Decoding does not reject such a message: a TSIG that is not the last record on the wire raises "misplaced or corrupt TSIG", but the error is caught, reported as a warning, and the record is left in the packet. RFC 8945 section 5.2 requires the message to be dropped. The recursion is reached only when the decoded TSIG carries an empty MAC, since a MAC recovered from the wire short-circuits the signing step. It is reached only from code that re-encodes a message it decoded, such as a forwarder or a proxy. A decoded message that is never re-encoded is unaffected. Message direction does not matter: a query reaches the same path as a response. Each cycle re-encodes the whole message, so fewer than 100 bytes on the wire exhaust available memory and terminate the process.

Ein entfernter, anonymer Angreifer kann eine Schwachstelle in Red Hat Enterprise Linux ausnutzen, um einen Denial of Service Angriff durchzuführen.