CVE-2023-23931: Cryptography.io Cryptography

Medium severity, CVSS 6.5. EPSS: 1.3% chance of exploitation in the next 30 days.

cryptography is a package designed to expose cryptographic primitives and recipes to Python developers. In affected versions `Cipher.update_into` would accept Python objects which implement the buffer protocol, but provide only immutable buffers. This would allow immutable objects (such as `bytes`) to be mutated, thus violating fundamental rules of Python and resulting in corrupted output. This now correctly raises an exception. This issue has been present since `update_into` was originally introduced in cryptography 1.8.

Affected products

• Cryptography.io Cryptography: from 1.8, before 39.0.1 (fixed in 39.0.1)

Published 2023-02-07. Last modified 2026-06-17.