critical CVSS 9.8

CVE-2026-39892·Python vulnerability

cryptography is a package designed to expose cryptographic primitives and recipes to Python developers. From 45.0.0 to before 46.0.7, if a non-contiguous buffer was passed to APIs which accepted Python buffers (e.g. Hash.update()), this could lead to buffer overflows. This vulnerability is fixed in 46.0.7.

Severity
critical
Software
Python
Fixed in
46.0.7
Published
2026-04-08

Affected versions

From: 45.0.0

Until: 46.0.7

Fixed in: 46.0.7

How to fix this CVE

Update the Python cryptography package to version 46.0.7 or later to patch a critical buffer overflow vulnerability in buffer-handling APIs. This fix prevents potential memory corruption when non-contiguous buffers are passed to cryptographic functions like Hash.update(). Prioritize this update immediately due to the critical CVSS score of 9.8.

sudo dnf update python3-cryptography

Defensia detects this vulnerability

How to check if you are affected

  1. Check the installed cryptography package version: python3 -c "import cryptography; print(cryptography.__version__)"
  2. Verify if your application uses the cryptography module by searching for imports: grep -r "from cryptography" /path/to/application && grep -r "import cryptography" /path/to/application
  3. Review application logs for crashes or segmentation faults occurring in cryptographic operations between April 2026 and the patch date
  4. Confirm the fix by re-running the version check and verifying it reports 46.0.7 or higher

FAQ

What is CVE-2026-39892?

CVE-2026-39892 is a critical buffer overflow vulnerability in the Python cryptography library (versions 45.0.0–46.0.6) that occurs when non-contiguous memory buffers are provided to cryptographic APIs, potentially leading to memory corruption and unauthorized code execution.

Is CVE-2026-39892 being actively exploited?

No, this vulnerability is not currently listed on the CISA Known Exploited Vulnerabilities catalog, and no public exploits have been disclosed. However, its critical CVSS score warrants immediate patching.

What versions of Python are affected by CVE-2026-39892?

The cryptography package versions 45.0.0 through 46.0.6 are vulnerable. The vulnerability is patched in cryptography version 46.0.7 and later.

How do I check if my server is vulnerable to CVE-2026-39892?

Run: python3 -c "import cryptography; v = tuple(map(int, cryptography.__version__.split('.')[:2])); print('VULNERABLE' if v >= (45, 0) and v < (46, 1) else 'PATCHED')" — if it returns 'VULNERABLE', update immediately.

Does Defensia detect CVE-2026-39892?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If the cryptography module is installed on a monitored server, CVE-2026-39892 will appear in your dashboard with remediation steps.

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References

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