What’s Vulnerable › Vulnerabilities

CVE-2020-25659: RSA decryption vulnerable to Bleichenbacher timing vulnerability

• Severity: medium (CVSS 5.9 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 2.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-01-11 · updated 2026-06-17
• Weakness: CWE-385

Description

python-cryptography 3.2 is vulnerable to Bleichenbacher timing attacks in the RSA decryption API, via timed processing of valid PKCS#1 v1.5 ciphertext.

Affected products

• pyca cryptography: 3.2
• Oracle Communications Cloud Native Core Network Function Cloud Native Environment: 1.10.0
• Pypi Cryptography: before 3.2.1; 0.1, 0.2, 0.2.1, 0.2.2, 0.3, 0.4 (+74) — fixed in 3.2.1

How to fix

Upgrade to a fixed version: Pypi Cryptography 3.2.1. Check the vendor advisory for mitigations.

References

• https://github.com/pyca/cryptography/pull/5507/commits/ce1bef6f1ee06ac497ca0c837fbd1c7ef6c2472b
• https://www.oracle.com/security-alerts/cpuapr2022.html
• https://www.oracle.com/security-alerts/cpujul2022.html
• https://github.com/pyca/cryptography/pull/5507/commits/ce1bef6f1ee06ac497ca0c837fbd1c7ef6c2472b
• https://www.oracle.com/security-alerts/cpuapr2022.html
• https://www.oracle.com/security-alerts/cpujul2022.html

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