Traffic decryption via predictable Diffie-Hellman keys
Published Jun 30, 2026 · Updated Jun 30, 2026
Weak key generation in Net::BitTorrent through 2.0.1 allows remote attackers to decrypt MSE peer traffic by observing a handshake. KeyExchange.pm draws the 160-bit Diffie-Hellman private key from Perl rand(), while _random_pad exposes subsequent output from the same predictable process-wide sequence in cleartext. A passive network observer can reconstruct the generator state, compute the shared secret from the public key on the wire, and decrypt the connection; no traffic modification or host access is required.
Summary
What happened
Weak key generation in Net::BitTorrent through 2.0.1 allows remote attackers to decrypt MSE peer traffic by observing a handshake. KeyExchange.pm draws the 160-bit Diffie-Hellman private key from Perl rand(), while _random_pad exposes subsequent output from the same predictable process-wide sequence in cleartext. A passive network observer can reconstruct the generator state, compute the shared secret from the public key on the wire, and decrypt the connection; no traffic modification or host access is required.
The record
- CVE
- CVE-2026-57082
- Published
- Jun 30, 2026
- Updated
- Jun 30, 2026
- Vendor
- Sanko Robinson
- Product
- Net::BitTorrent
- Classifications
- CWE-330, CWE-338, T1040
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 30, 2026CVE publishedPublication date reported by the CVE source.
- Jun 30, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <=2.0.1
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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