Thinbus generates insufficient entropy: 252 bits vs minimum 256 bits
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- High
- Attack requirements
- None
- Impact type
- —
- Confidentiality · integrity · availability
- High · High · None
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| simbo1905 | thinbus-srp-npm | before 2.0.1 | 2.0.1 | Patch available | CNA |
| — | thinbus-srp (npm) | before 2.0.1 | 2.0.1 | Patch available | GHSA-8q6v-474h-whgg |
- thinbus-srp-npm Vendorsimbo1905 Affected before 2.0.1 Fixed in 2.0.1 Patch available CNA
- thinbus-srp (npm) Vendor— Affected before 2.0.1 Fixed in 2.0.1 Patch available GHSA-8q6v-474h-whgg
Remediation
- Fix · CNA thinbus-srp-npm (simbo1905) Fixed in 2.0.1
- Fix · GHSA-8q6v-474h-whgg thinbus-srp (npm) Fixed in 2.0.1 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2025-54885
- 2026-10-03 Alias added: GHSA-8q6v-474h-whgg
References
Other 5
- https://github.com/simbo1905/thinbus-srp-npm/security/advisories/GHSA-8q6v-474h-whgg
- 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/commit/aa7064c1db7294ce867e9bc92f26fa6c71a5a2cb
- https://github.com/simbo1905/thinbus-srp-npm
Sources
- CVE-2025-54885 · CVE Program
- CVE-2025-54885 · NVD
- FIRST EPSS
- GHSA-8q6v-474h-whgg · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences