CVE-2026-57080
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 · uneditedNet::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.
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 confidenceThe Net::BitTorrent library's peer-wire message decoder trusts the 4-byte length prefix from peers without validating an upper bound. An attacker can announce a message length of up to ~4 GiB, causing the receive_data function to accumulate unbounded data in the input buffer until memory is exhausted. Since peer connections are unauthenticated, any peer in the swarm can trigger this condition.
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 checksWork through these to decide whether this CVE applies to you.
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Identify Net::BitTorrent installationRun `perl -MNet::BitTorrent -e 'print $Net::BitTorrent::VERSION'` or check your system's package manager for the installed Net::BitTorrent packageAffected if Net::BitTorrent version is 2.0.1 or lower (any version through 2.0.1 is affected)
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Confirm peer-wire protocol is in useDetermine whether your application uses Net::BitTorrent to accept or process incoming peer connections; check application logs, running processes, or configuration for active BitTorrent client behaviorAffected if Net::BitTorrent is actively handling peer connections
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Inspect message length validationExamine the Net::BitTorrent source code (typically in the peer-wire protocol handler) for the routine that parses the 4-byte message length prefix; look for a bounds check that rejects or truncates lengths exceeding a reasonable maximum (such as 16 KiB plus protocol overhead) before buffer allocationAffected if No maximum length validation exists on the peer-wire message length prefix before buffer allocation
You are affected if Net::BitTorrent version 2.0.1 or lower is installed and actively handling peer connections without bounds checking on the 4-byte length prefix.
Generated from the published advisory. Verify against your own configuration.
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 dataImplement a maximum message length cap (e.g., 16 KiB + overhead) in the _process_messages function to reject anomalous length prefixes before buffer allocation, and add input validation in receive_data to abort connections that exceed reasonable memory bounds.
- Consultation2.0 h
- Implementation3.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,272.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-57080 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-57080 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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