# CVE-2026-57079: Net::BitTorrent path traversal in peer-supplied metadata

Source: https://junglewise.ai/threats/cve-2026-57079-net-bittorrent-path-traversal-in-peer-supplied-metadata  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-30. Updated: 2026-06-30  
License: CC BY 4.0 with a link back

CVE-2026-57079 · Severity: info · CVSS 9.8 · Published 2026-06-30

Net::BitTorrent is a Perl library used to download files via the BitTorrent protocol. A security flaw allows a malicious peer or a specially crafted magnet link to trick the software into writing files to any location on the user's computer instead of the intended download folder. This could allow an attacker to gain full control over the system by overwriting sensitive configuration files or adding malicious scripts.

Technologies: [SANKO Net::BitTorrent](https://junglewise.ai/threats/technologies/net-bittorrent). Vendors: [SANKO](https://junglewise.ai/threats/vendors/sanko).

## Quick answers

**Is CVE-2026-57079 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-57079 being exploited in the wild.

**How severe is CVE-2026-57079?** Informational severity, with a CVSS score of 9.8, published 30 June 2026.

**Which products and versions are affected?** SANKO Net::BitTorrent <= 2.0.1.

**Is there a fix for CVE-2026-57079?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-57079 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-57079?** Check whether you run SANKO Net::BitTorrent at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

Net::BitTorrent versions through 2.0.1 contain a path traversal vulnerability in the metadata-ingest path used for magnet links and peer-to-peer metadata exchange (BEP09). While the library validates .torrent files, the '_on_metadata_received' routine fails to sanitize file names containing '..' segments. These names are passed to 'Path::Tiny::child', which does not collapse parent directory references, allowing files to be written outside the designated download directory. Because the attacker provides both the metadata (including file hashes) and the file content, the client's integrity checks pass, enabling the creation or overwriting of arbitrary files such as cron jobs or SSH keys, leading to remote code execution.

## Affected products

- SANKO Net::BitTorrent <= 2.0.1

## Timeline

- 2026-06-28: advisory: GitHub Security Advisory published by vendor
- 2026-06-30: disclosed: CVE published to NVD dataset

## References

- [https://cpan.org/modules](https://cpan.org/modules)
- [https://github.com/sanko/Net-BitTorrent.pm/security/advisories/GHSA-5wc6-r65f-62rr](https://github.com/sanko/Net-BitTorrent.pm/security/advisories/GHSA-5wc6-r65f-62rr)

## Related threats

- [SANKO Net::BitTorrent predictable PRNG in MSE handshake](https://junglewise.ai/threats/cve-2026-57082-sanko-net-bittorrent-predictable-prng-in-mse-handshake)
- [SANKO Net::BitTorrent memory exhaustion via nested bencoded input](https://junglewise.ai/threats/cve-2026-57081-sanko-net-bittorrent-memory-exhaustion-via-nested-bencoded-input)
- [SANKO Net::BitTorrent memory exhaustion in peer-wire framing](https://junglewise.ai/threats/cve-2026-57080-sanko-net-bittorrent-memory-exhaustion-in-peer-wire-framing)