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CVE-2023-23931 Moderate

CVE-2023-23931

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.

Exploit probability 1.3%
Published February 7, 2023
Required by Not available
Last source change February 22, 2026

02 / AFFECTED SOFTWARE

Affected packages

Unknown Unknown

24 explicit affected versions

PyPI cryptography

61 explicit affected versions

PyPI cryptography

61 explicit affected versions

03 / CONNECTIONS

Connected vulnerabilities

04 / EVIDENCE

Source records

Open Source Vulnerabilities CVE-2023-23931

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.

View original source
Open Source Vulnerabilities GHSA-w7pp-m8wf-vj6r

Previously, `Cipher.update_into` would accept Python objects which implement the buffer protocol, but provide only immutable buffers: ```pycon >>> outbuf = b"\x00" * 32 >>> c = ciphers.Cipher(AES(b"\x00" * 32), modes.ECB()).encryptor() >>> c.update_into(b"\x00" * 16, outbuf) 16 >>> outbuf b'\xdc\x95\xc0x\xa2@\x89\x89\xadH\xa2\x14\x92\x84 \x87\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00' ``` This would allow immutable objects (such as `bytes`) to be mutated, thus violating fundamental rules of Python. This is a soundness bug -- it allows programmers to misuse an API, it cannot be exploited by attacker controlled data alone. This now correctly raises an exception. This issue has been present since `update_into` was originally introduced in cryptography 1.8.

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Open Source Vulnerabilities PYSEC-2023-11

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.

View original source

05 / REFERENCES

Further evidence