CPANSA-Net-BitTorrent-2026-57079: Net-BitTorrent vulnerability

Publisher giterlizzi Document category csaf_security_advisory
Initial release date 2026-06-30T00:00:00 Engine CSAF Perl Toolkit 0.26
Current release date 2026-06-30T00:00:00 Build Date
Current version 1 Status final
CVSS v3.1 Base Score 5.3 Severity
Original language Language en
Also referred to

Vulnerability Description

Net::BitTorrent versions through 2.0.1 for Perl write files outside the download directory via path traversal in peer-supplied metadata. Net::BitTorrent validates file path components only on the .torrent-file ingest path. The peer and magnet metadata path (_on_metadata_received, reached from the BEP09 ut_metadata extension) passes attacker-supplied file names straight to Storage::add_file and Storage::_parse_file_tree, where Path::Tiny's child() does not collapse "..". A v2 file tree key, a v1 files[].path element, or a single-file name containing ".." segments therefore resolves outside the download directory. Because the peer also controls the piece hashes and the served bytes, content verification passes, so a malicious magnet or peer writes attacker-chosen content to an attacker-chosen path on the downloading host.

Vulnerabilities

CVE-2026-57079

Vulnerability Description

Net::BitTorrent versions through 2.0.1 for Perl write files outside the download directory via path traversal in peer-supplied metadata.

Net::BitTorrent validates file path components only on the .torrent-file ingest path. The peer and magnet metadata path (_on_metadata_received, reached from the BEP09 ut_metadata extension) passes attacker-supplied file names straight to Storage::add_file and Storage::_parse_file_tree, where Path::Tiny's child() does not collapse "..". A v2 file tree key, a v1 files[].path element, or a single-file name containing ".." segments therefore resolves outside the download directory.

Because the peer also controls the piece hashes and the served bytes, content verification passes, so a malicious magnet or peer writes attacker-chosen content to an attacker-chosen path on the downloading host.

Weakness CWE-22 : Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

Product status

Known affected
Product Score
Net-BitTorrent greater than 0
CVSS Version CVSS Vector CVSS Base Score CVSS Base Severity
3.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N 5.3 Medium

giterlizzi

Namespace: https://github.com/giterlizzi/

gdt@cpan.org

References

Revision history

Version Date of the revision Summary of the revision
1 Tue Jun 30 00:00:00 2026 First release

Sharing rules

TLP:WHITE
For the TLP version see: https://www.first.org/tlp/