CVE-2026-39892

Modified Modified - Updated After Analysis

Buffer Overflow in Python cryptography Package Before

Publication date: 2026-04-08

Last updated on: 2026-07-01

Assigner: GitHub, Inc.

Description

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.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-04-08

Last Modified

2026-07-01

Generated

2026-07-06

AI Q&A

2026-04-09

EPSS Evaluated

2026-07-05

NVD

CVE-2026-39892

Affected Vendors & Products

Vendor	Product	Version / Range
cryptography.io	cryptography	From 45.0.0 (inc) to 46.0.7 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-131	The product does not correctly calculate the size to be used when allocating a buffer, which could lead to a buffer overflow.
CWE-119	The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.

Attack-Flow Graph

Impact Analysis

The buffer overflow vulnerability could allow an attacker to cause a crash or potentially execute arbitrary code when the affected cryptography APIs process non-contiguous buffers.

Since the cryptography package is used to perform cryptographic operations, exploitation of this vulnerability could compromise the security of applications relying on it.

The CVSS v4.0 base score of 6.9 indicates a medium to high severity impact, meaning it is a significant security risk if left unpatched.

Executive Summary

This vulnerability exists in the cryptography package for Python, specifically in versions from 45.0.0 up to but not including 46.0.7. When a non-contiguous buffer is passed to certain APIs that accept Python buffers, such as the Hash.update() function, it can cause a buffer overflow.

A buffer overflow occurs when more data is written to a buffer than it can hold, potentially leading to unexpected behavior or security issues.

This issue was fixed in version 46.0.7 of the cryptography package.

Mitigation Strategies

To mitigate this vulnerability, upgrade the cryptography package to version 46.0.7 or later, where the buffer overflow issue has been fixed.

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