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Net-BitTorrent-v2.1.0
⭐ Starred 13 / Net::BitTorrent::Tracker::HTTP
Security Advisories (2)
CVE-2026-57080 (2026-06-30)

Net::BitTorrent versions through 2.1.0 for Perl allow remote memory exhaustion via an uncapped peer-wire message-length prefix. The peer-wire framing in _process_messages trusts the 4-byte length prefix sent by a connected peer with no upper bound, while receive_data appends every inbound byte to the input buffer. A peer announces a length prefix of up to about 4 GiB and then streams bytes; the decoder waits until the buffer holds the full message before processing it, so the buffer grows without limit. Peer connections are unauthenticated, so any peer in the swarm exhausts the downloading process's memory. The largest legitimate message is a 16 KiB piece block, so any announced length far above that is anomalous.

CVE-2026-57081 (2026-06-30)

Net::BitTorrent versions through 2.1.0 for Perl allow remote memory exhaustion via deeply nested bencoded input. bdecode recurses once per nested list or dictionary level with no depth cap, and each recursive call receives the remaining buffer by value while the list and dictionary branches capture the whole remainder, so every live recursion frame keeps its own copy of the shrinking buffer (O(N^2) bytes for an N-deep input). The decoder runs on every untrusted bencode source: .torrent files, BEP09 metadata fetched from peers, DHT messages, and tracker responses. A bencoded input of roughly 150,000 nested lists (about 150 KB on the wire) drives multi-gigabyte peak memory, so one short message from any peer, or one crafted .torrent file or magnet link, terminates the client.

NAME

Net::BitTorrent::Tracker::HTTP - HTTP/HTTPS BitTorrent Tracker Protocol

SYNOPSIS

use Net::BitTorrent::Tracker::HTTP;

my $tracker = Net::BitTorrent::Tracker::HTTP->new(
    url => 'https://tracker.example.com/announce'
);

# Perform announce
$tracker->perform_announce({
    infohash   => $ih,
    peer_id    => $id,
    port       => 6881,
    downloaded => 0,
    uploaded   => 0,
    left       => 1024
}, sub ($res) {
    say 'Interval: ' . $res->{interval};
});

DESCRIPTION

Net::BitTorrent::Tracker::HTTP implements the original BitTorrent tracker protocol over HTTP and HTTPS. It handles URL encoding of binary infohashes and parsing of bencoded responses.

METHODS

new( %params )

Creates a new HTTP tracker object.

my $tracker = Net::BitTorrent::Tracker::HTTP->new( url => $url );

Expected parameters:

url

The tracker announce URL.

perform_announce( \%params, [$callback] )

Sends an announce request to the HTTP tracker.

$tracker->perform_announce( \%params, sub ($res) { ... } );

Expected parameters:

\%params

Standard announce parameters. Automatically handles compact peer lists (IPv4 and IPv6) and supports asynchronous mode if $params-{ua}> is provided (e.g., an instance of Mojo::UserAgent).

$callback - optional

Called with the parsed response hash.

perform_scrape( \@infohashes, [$callback] )

Sends a scrape request to the HTTP tracker.

$tracker->perform_scrape( \@ihs, sub ($res) { ... } );

Executes a tracker scrape (BEP 48) by converting the announce URL to a scrape URL and requesting statistics for the provided hashes.

Expected parameters:

\@infohashes

List of infohashes to scrape.

$callback - optional

Called with the scrape results.

build_announce_url( $params )

Generates the full announce URL with query parameters.

my $url = $tracker->build_announce_url( \%params );

Correctly percent-encodes the binary info_hash and peer_id fields.

Expected parameters:

$params

Hash reference of announce parameters.

build_scrape_url( $infohashes )

Generates the scrape URL for the given infohashes.

my $url = $tracker->build_scrape_url( \@ihs );

Expected parameters:

$infohashes

Array reference of binary infohashes.

parse_response( $data )

Decodes and parses a tracker response.

my $dict = $tracker->parse_response( $raw_data );

Automatically expands compact peer lists into user-friendly hashrefs.

Expected parameters:

$data

The raw bencoded response string.

SPECIFICATIONS

  • BEP 03: The BitTorrent Protocol (HTTP Tracker)

  • BEP 23: Tracker Returns Compact Peer Lists

  • BEP 07: IPv6 Support (peers6 field)

  • BEP 48: Tracker Scrape Convention

AUTHOR

Sanko Robinson - https://github.com/sanko

COPYRIGHT

Copyright (C) 2008-2026 by Sanko Robinson.

This library is free software; you can redistribute it and/or modify it under the terms of the Artistic License 2.0.