SANKO Net::BitTorrent up to 2.0.1 on Perl Private Key KeyExchange.pm rand weak prng

Summaryinfo

A vulnerability, which was classified as problematic, was found in SANKO Net::BitTorrent up to 2.0.1 on Perl. Affected is the function rand of the file KeyExchange.pm of the component Private Key Handler. Executing a manipulation can lead to weak prng. The identification of this vulnerability is CVE-2026-57082. The attack may be launched remotely. There is no exploit available.

Detailsinfo

A vulnerability classified as problematic was found in SANKO Net::BitTorrent up to 2.0.1 on Perl. This vulnerability affects the function rand of the file KeyExchange.pm of the component Private Key Handler. The manipulation with an unknown input leads to a weak prng vulnerability. The CWE definition for the vulnerability is CWE-338. The product uses a Pseudo-Random Number Generator (PRNG) in a security context, but the PRNG's algorithm is not cryptographically strong. As an impact it is known to affect confidentiality. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-57082 since 06/23/2026. The exploitation appears to be difficult. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1600.001.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-40291). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Type

• Peer-to-Peer Software

Vendor

• SANKO

Name

• Net::BitTorrent

Version

• 2.0.0
• 2.0.1

CPE 2.3info

• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

VulDB is the best source for vulnerability data and more expert information about this specific topic.

Discussion