CVE-2026-81928 Affecting libnet-dns-perl package, versions *


Severity

Recommended
low

Based on Debian security rating.

Threat Intelligence

EPSS
0.68% (53rd percentile)

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  • Snyk IDSNYK-DEBIAN13-LIBNETDNSPERL-19498560
  • published2 Sept 2026
  • disclosed2 Sept 2026

Introduced: 2 Sep 2026

CVE-2026-81928  (opens in a new tab)

How to fix?

There is no fixed version for Debian:13 libnet-dns-perl.

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 Debian. See How to fix? for Debian:13 relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1