dbcve.org
Uncontrolled Resource ConsumptionWeakness · CWE-400

CVE-2026-57081

HIGH · 7.5 CVSS v3.1 Published 2026-06-30
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click 7 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Net::BitTorrent versions up to 2.1.0 contain a memory exhaustion vulnerability in the bdecode bencode parser. The decoder uses recursive functions without depth limiting, and each recursive call receives the buffer by value while nested list/dictionary branches capture the entire remainder, causing O(N²) memory consumption. Attackers can trigger multi-gigabyte memory usage from a ~150KB malicious bencoded input from peers, .torrent files, DHT messages, or tracker responses.

MitigationImplement iterative bencode parsing with a configurable maximum nesting depth cap to prevent unbounded recursion and buffer copying. Until patched, avoid processing bencoded data from untrusted sources.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify Net::BitTorrent library usage
    Search your codebase for references to Net::BitTorrent, require/import statements for 'Net::BitTorrent' or 'bdecode', and review any torrent parsing functionality
    Affected if Net::BitTorrent library is used for parsing bencoded data such as torrent files, DHT responses, or tracker data
  2. Determine installed Net::BitTorrent version
    Run your package manager or check your dependency lock file (e.g., cpanfile, META.json, or equivalent) for the Net::BitTorrent version number
    Affected if The installed version is unknown or falls within any vulnerable range (no fixed version provided)
  3. Verify bdecode function is exposed to untrusted input
    Review code paths where bdecode is called; check if it processes data from external sources like torrent file uploads, peer connections, DHT queries, or tracker responses
    Affected if bdecode parses bencode data from any source outside your trusted control boundary
  4. Inspect bdecode implementation for depth limiting
    Examine the bdecode source code (check for recursion depth counters, max depth parameters, or depth limit constants)
    Affected if No depth limiting mechanism exists in the bdecode function or surrounding wrapper code
  5. Test memory behavior with deeply nested bencode
    Create a test bencode payload with 150,000+ nested levels (~150KB) and feed it to bdecode while monitoring memory consumption
    Affected if Memory usage grows proportionally to nesting depth or exceeds expected buffer size significantly

You are affected if your environment uses Net::BitTorrent's bdecode to parse untrusted bencoded data without depth limiting implemented.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Implement iterative bencode parsing with a configurable maximum nesting depth cap to prevent unbounded recursion and buffer copying. Until patched, avoid processing bencoded data from untrusted sources.

Have this fixed Scoped from the published advisory
  • Consultation4.0 h
  • Implementation12.0 h
  • Testing6.0 h
  • Review / QA3.0 h
25.0 hours of engineering $4,400
Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $7,040.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2026-57081 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-57081 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data