Nutshell: Improper Validation of Specified Quantity in Input
CVE-2025-65548 is a critical-severity improper validation of specified quantity in input vulnerability in Nutshell from Cashu, with a CVSS 3.1 base score of 9.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 0.18.0 as the first without the flaw, so updating Nutshell to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.45% chance of exploitation within 30 days, which is low compared with other CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update Nutshell to 0.18.0 or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
Version data comes from NVD's product matching. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N. Scored by CISA (ADP).
Official description
NUT-14 allows cashu tokens to be created with a preimage hash. However, nutshell (cashubtc/nuts) before 0.18.0 do not validate the size of preimage when the token is spent. The preimage is stored by the mint and attacker can exploit this vulnerability to fill the mint's db nd disk with arbitrary data.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Validation of Specified Quantity in Input
The product receives input that is expected to specify a quantity (such as size or length), but it does not validate or incorrectly validates that the quantity has the required properties.
More Improper Validation of Specified Quantity in Input vulnerabilities (CWE-1284)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Technical write-ups (may include proof of concept)
- bitcointalk.org/index.php?topic=5564329Exploit, Issue Tracking
- github.com/cashubtc/nuts/blob/main/07.mdExploit, Third Party Advisory
- github.com/cashubtc/nuts/blob/main/14.mdExploit, Third Party Advisory
- github.com/jamesob/delving-bitcoin-archive/blob/master/archive/rendered-topics/2025-11-November/2025-11-02-pu…Exploit, Third Party Advisory
Other references
- preimage007.github.io/Product
Recent Improper Validation of Specified Quantity in Input vulnerabilities
- 7.5 High severity
- 8.6 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
Spotted an error? Tell us.