CVE-2026-78030

/// Technical description

DBI versions before 1.653 for Perl load arbitrary modules via unvalidated dbm_type and dbm_mldbm attributes in DBD::DBM.

DBD::DBM passes the dbm_type and dbm_mldbm connect attributes to require without checking that the value names a module. require treats a path-shaped string as a literal filename and does not consult @INC, so the attribute chooses the file that Perl loads and runs.

The MLDBM::Serializer:: prefix that DBD::DBM prepends to dbm_mldbm is not a boundary: only the :: separators are rewritten to /, so a value containing / traverses out of the serializer directory. The value is also assigned to $MLDBM::Serializer, which MLDBM requires the same way when it ties the table.

A caller that lets an untrusted party influence either attribute, for example through a DSN fragment or a parameter that selects a storage backend, runs the file-scope code of whatever module the value names.

For example,

my $dsn = "dbi:DBM:f_dir=/var/db;dbm_type=../../Untrusted.pm"

my $dbh = DB

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References