Vulnerability in Sanko Net::bittorrent
CVE-2026-57082
Net::BitTorrent versions before 2.1.0 for Perl generate the MSE Diffie-Hellman private key with a non-cryptographic PRNG. The MSE (Message Stream Encryption) handshake derives its 160-bit Diffie-Hellman private key from Perl's rand(), a non-cryptographic drand48-class generator seeded once per process, in KeyExchange.pm. The shared secret and the RC4 keys derived from it (the SHA-1 of "keyA" or "keyB", the shared secret, and the infohash) therefore depend entirely on a predictable PRNG. The same handshake sends, in cleartext, random padding drawn from the same rand() sequence in _random_pad, immediately after the public key and the private-key draw. A passive observer of the handshake recovers the PRNG state from the cleartext padding, reconstructs the private key, computes the shared secret from the peer's public key on the wire, derives the RC4 keys, and decrypts the connection, defeating the passive-observation obfuscation MSE provides.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N.
EPSS exploit prediction
EPSS: 0.002 (13.0th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 13th percentile — 13.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000
Affected products
- Sanko Net::bittorrent — versions 0
Weakness classification (CWE)
References
- 9b29abf9-4ab0-4765-b253-1875cd9b441e (vendor-advisory)
- 9b29abf9-4ab0-4765-b253-1875cd9b441e (release-notes)
Frequently asked questions
- What is CVE-2026-57082?
- CVE-2026-57082 is a medium-severity vulnerability in Sanko Net::bittorrent, classified under Use of Insufficiently Random Values. CVSS score: 5.9/10. Published 2026-06-30.
- How severe is CVE-2026-57082?
- Medium severity. CVSS v3 base score is 5.9 out of 10.