What’s Vulnerable › Vulnerabilities

CVE-2020-36242: PyCA Cryptography symmetrically encrypting large values can lead to integer overflow

• Severity: critical (CVSS 9.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 6.7% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2021-02-07 · updated 2026-06-17
• Weakness: CWE-190

Description

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.

Affected products

• pyca cryptography: before 3.3.2 — fixed in 3.3.2
• Fedoraproject Fedora: 33
• Oracle Communications Cloud Native Core Network Function Cloud Native Environment: 1.10.0
• Pypi Cryptography: from 3.1 before 3.3.2; 3.1, 3.1.1, 3.2, 3.2.1, 3.3, 3.3.1 — fixed in 3.3.2

How to fix

Upgrade to a fixed version: pyca cryptography 3.3.2; Pypi Cryptography 3.3.2. Check the vendor advisory for mitigations.

References

• https://github.com/pyca/cryptography/blob/master/CHANGELOG.rst
• https://github.com/pyca/cryptography/compare/3.3.1...3.3.2
• https://github.com/pyca/cryptography/issues/5615
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/L7RGQLK4J5ZQFRLKCHVVG6BKZTUQMG7E/
• https://www.oracle.com/security-alerts/cpuapr2022.html
• https://www.oracle.com/security-alerts/cpujul2022.html
• https://github.com/pyca/cryptography/blob/master/CHANGELOG.rst
• https://github.com/pyca/cryptography/compare/3.3.1...3.3.2
• https://github.com/pyca/cryptography/issues/5615
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/L7RGQLK4J5ZQFRLKCHVVG6BKZTUQMG7E/
• https://www.oracle.com/security-alerts/cpuapr2022.html
• https://www.oracle.com/security-alerts/cpujul2022.html

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