What’s Vulnerable › Vulnerabilities

CVE-2025-54885: Thinbus generates insufficient entropy: 252 bits vs minimum 256 bits

• Severity: medium (CVSS 6.9 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-08-07 · updated 2026-06-17
• Weakness: CWE-331

Description

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.

Affected products

• simbo1905 thinbus-srp-npm: before 2.0.1

References

• https://github.com/simbo1905/thinbus-srp-npm/issues/28
• https://github.com/simbo1905/thinbus-srp-npm/pull/30/commits/4aeaea2366e090765a8204059c7bcf3616438d31
• https://github.com/simbo1905/thinbus-srp-npm/security/advisories/GHSA-8q6v-474h-whgg

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