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

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MEDIUM

Thinbus generates insufficient entropy: 252 bits vs minimum 256 bits

Published Aug 7, 2025

6.9

MEDIUM

CVSS 4.0

EPSS 0.37%

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

Vendor Simbo1905 Product Thinbus-Srp-Npm Default
n/a
- Version
  < 2.0.1
  Status
  affected
  Constraints
  -

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor

Product

Default status

Versions

Simbo1905

Thinbus-Srp-Npm

n/a

Version	Status	Constraints
< 2.0.1	affected	-

Ecosystem	Package	Introduced	Fixed
npm	thinbus-srp	0	2.0.1

Remediation

No remediation recorded yet.

Weaknesses (1)

CWE-331

References (7)

Link	Providers	Tags
https://euvd.enisa.europa.eu/vulnerability/EUVD-2025-23897		Advisory
https://github.com/advisories/GHSA-8q6v-474h-whgg		Advisory
https://github.com/simbo1905/thinbus-srp-npm/commit/aa7064c1db7294ce867e9bc92f26fa6c71a5a2cb
https://github.com/simbo1905/thinbus-srp-npm/issues/28		x_refsource_MISC
https://github.com/simbo1905/thinbus-srp-npm/pull/30/commits/4aeaea2366e090765a8204059c7bcf3616438d31		x_refsource_MISC
https://github.com/simbo1905/thinbus-srp-npm/security/advisories/GHSA-8q6v-474h-whgg		x_refsource_CONFIRM
https://nvd.nist.gov/vuln/detail/CVE-2025-54885