Perl DBI <1.653 DBD::DBM Allows Arbitrary Module Load (AML)
CVE-2026-78030 Published on September 19, 2026
DBI versions before 1.653 for Perl load arbitrary modules via unvalidated dbm_type and dbm_mldbm attributes in DBD::DBM
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 = DBI->connect( $dsn );
Note that DBD::Gofer forwards connect attributes to the server side, and DBI::ProxyServer checks only that a DSN starts with a driver prefix.
Weakness Type
What is a Reflection Injection Vulnerability?
The application uses external input with reflection to select which classes or code to use, but it does not sufficiently prevent the input from selecting improper classes or code. If the application uses external inputs to determine which class to instantiate or which method to invoke, then an attacker could supply values to select unexpected classes or methods. If this occurs, then the attacker could create control flow paths that were not intended by the developer. These paths could bypass authentication or access control checks, or otherwise cause the application to behave in an unexpected manner. This situation becomes a doomsday scenario if the attacker can upload files into a location that appears on the application's classpath (CWE-427) or add new entries to the application's classpath (CWE-426). Under either of these conditions, the attacker can use reflection to introduce new, malicious behavior into the application.
CVE-2026-78030 has been classified to as a Reflection Injection vulnerability or weakness.
Products Associated with CVE-2026-78030
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