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CVE-2020-36242 Critical

CVE-2020-36242

In the cryptography package before 3.3.2 for Python, certain sequences of update calls to symmetrically encrypt multi-GB values could result in an integer overflow and buffer overflow, as demonstrated by the Fernet class.

Exploit probability 6.7%
Published February 7, 2021
Required by Not available
Last source change August 7, 2026

02 / AFFECTED SOFTWARE

Affected packages

Unknown Unknown

37 explicit affected versions

PyPI cryptography

6 explicit affected versions

PyPI cryptography

6 explicit affected versions

03 / CONNECTIONS

Connected vulnerabilities

04 / EVIDENCE

Source records

Open Source Vulnerabilities GHSA-rhm9-p9w5-fwm7

cryptography is a package designed to expose cryptographic primitives and recipes to Python developers. When certain sequences of `update()` calls with large values (multiple GBs) for symetric encryption or decryption occur, it's possible for an integer overflow to happen, leading to mishandling of buffers. This is patched in version 3.3.2 and newer.

View original source
Open Source Vulnerabilities PYSEC-2021-63

In the cryptography package before 3.3.2 for Python, certain sequences of update calls to symmetrically encrypt multi-GB values could result in an integer overflow and buffer overflow, as demonstrated by the Fernet class.

View original source
Open Source Vulnerabilities CVE-2020-36242

In the cryptography package before 3.3.2 for Python, certain sequences of update calls to symmetrically encrypt multi-GB values could result in an integer overflow and buffer overflow, as demonstrated by the Fernet class.

View original source

05 / REFERENCES

Further evidence