CVE-2026-57081 PUBLISHED

Net::BitTorrent versions through 2.0.1 for Perl allow remote memory exhaustion via deeply nested bencoded input

Assigner: CPANSec
Reserved: 23.06.2026 Published: 30.06.2026 Updated: 30.06.2026

Net::BitTorrent versions through 2.0.1 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.

Product Status

Vendor SANKO
Product Net::BitTorrent
Versions Default: unaffected
  • affected from 0 to 2.0.1 (incl.)

Workarounds

There is no fixed release. Cap the bencode nesting depth (libtorrent rejects beyond about 100 levels) and decode without copying the buffer remainder at each level.

References

Problem Types

  • CWE-674 Uncontrolled Recursion CWE
  • CWE-400 Uncontrolled Resource Consumption CWE