CVE-2026-57082
Net::BitTorrent versions before 2.1.0 for Perl generate the MSE Diffie-Hellman private key with a non-cryptographic PRNG
Description
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.
INFO
Published Date :
June 30, 2026, 12:16 p.m.
Last Modified :
July 20, 2026, 7:16 a.m.
Remotely Exploit :
Yes !
Source :
9b29abf9-4ab0-4765-b253-1875cd9b441e
Affected Products
The following products are affected by CVE-2026-57082
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | 134c704f-9b21-4f2e-91b3-4a467353bcc0 |
Solution
- Update Net::BitTorrent to version 2.0.2 or later.
- Ensure the PRNG is properly seeded.
- Verify cryptographic key generation.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-57082.
| URL | Resource |
|---|---|
| https://github.com/sanko/Net-BitTorrent.pm/security/advisories/GHSA-g444-x2c5-94hc | |
| https://metacpan.org/release/SANKO/Net-BitTorrent-v2.1.0/changes |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-57082 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-57082
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-57082 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-57082 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 9b29abf9-4ab0-4765-b253-1875cd9b441e
Jul. 20, 2026
Action Type Old Value New Value Changed Affected [{'repo': 'https://github.com/sanko/Net-BitTorrent.pm', 'vendor': 'SANKO', 'product': 'Net::BitTorrent', 'versions': [{'status': 'affected', 'version': '0', 'versionType': 'custom', 'lessThanOrEqual': '2.0.1'}], 'packageName': 'Net-BitTorrent', 'programFiles': ['lib/Net/BitTorrent/Protocol/MSE/KeyExchange.pm', 'lib/Net/BitTorrent/Protocol/MSE.pm', 'lib/Net/BitTorrent/Peer.pm'], 'collectionURL': 'https://cpan.org/modules', 'defaultStatus': 'unaffected', 'programRoutines': [{'name': 'Net::BitTorrent::Protocol::MSE::_random_pad'}]}] [{'repo': 'https://github.com/sanko/Net-BitTorrent.pm', 'vendor': 'SANKO', 'product': 'Net::BitTorrent', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '2.1.0', 'versionType': 'custom'}], 'packageName': 'Net-BitTorrent', 'programFiles': ['lib/Net/BitTorrent/Protocol/MSE/KeyExchange.pm', 'lib/Net/BitTorrent/Protocol/MSE.pm', 'lib/Net/BitTorrent/Peer.pm'], 'collectionURL': 'https://cpan.org/modules', 'defaultStatus': 'unaffected', 'programRoutines': [{'name': 'Net::BitTorrent::Protocol::MSE::_random_pad'}]}] Changed Description Net::BitTorrent versions through 2.0.1 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. 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. Added Reference https://metacpan.org/release/SANKO/Net-BitTorrent-v2.1.0/changes -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 30, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N Added SSVC {'id': 'CVE-2026-57082', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-06-30T14:19:46.278267Z'} -
New CVE Received by 9b29abf9-4ab0-4765-b253-1875cd9b441e
Jun. 30, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://github.com/sanko/Net-BitTorrent.pm', 'vendor': 'SANKO', 'product': 'Net::BitTorrent', 'versions': [{'status': 'affected', 'version': '0', 'versionType': 'custom', 'lessThanOrEqual': '2.0.1'}], 'packageName': 'Net-BitTorrent', 'programFiles': ['lib/Net/BitTorrent/Protocol/MSE/KeyExchange.pm', 'lib/Net/BitTorrent/Protocol/MSE.pm', 'lib/Net/BitTorrent/Peer.pm'], 'collectionURL': 'https://cpan.org/modules', 'defaultStatus': 'unaffected', 'programRoutines': [{'name': 'Net::BitTorrent::Protocol::MSE::_random_pad'}]}] Added Description Net::BitTorrent versions through 2.0.1 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. Added CWE CWE-330 Added CWE CWE-338 Added Reference https://github.com/sanko/Net-BitTorrent.pm/security/advisories/GHSA-g444-x2c5-94hc