CVE-2025-54885CWE-331

Thinbus generates insufficient entropy: 252 bits vs minimum 256 bits

Medium · published August 7, 2025

CVSS v4.0
6.9
EPSS
0%
Percentile
31.3
In the wild
Unconfirmed
What it is

Thinbus Javascript Secure Remote Password is a browser SRP6a implementation for zero-knowledge password authentication. In versions 2.0.0 and below, a protocol compliance bug causes the client to generate a fixed 252 bits of entropy instead of the intended bit length of the safe prime (defaulted to 2048 bits). The client public value is being generated from a private value that is 4 bits below the specification. This reduces the protocol's designed security margin it is now practically exploitable. The servers full sized 2048 bit random number is used to create the shared session key and password proof. This is fixed in version 2.0.1.

The record
Technical detail
CVSS v4.0
6.9 · MEDIUM
Vector
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:U
EPSS
0.00385 · 31.3th percentile
Weakness
CWE-331 · Insufficient Entropy
Published
2025-08-07T00:02Z
EPSS history
Timeline
  • 07 AUG 00:02Z
    Thinbus generates insufficient entropy: 252 bits vs minimum 256 bits
    cvelistv5