CVE-2020-36242
CriticalSummary
In the cryptography package for Python before version 3.3.2, sequences of update calls for symmetric encryption of multi-GB data can cause integer overflow and buffer overflow, as demonstrated with the Fernet class.
Risk Assessment
An attacker could exploit this vulnerability to execute arbitrary code or cause a denial of service, posing a serious threat to the integrity and availability of systems using the cryptography library for large data encryption.
Recommendation
Immediately upgrade the cryptography package to version 3.3.2 or later to mitigate the buffer overflow risk.
Other vulnerabilities in cryptography
See all- CVE-2026-39892Critical
The cryptography library for Python versions 45.0.0 through 46.0.6 contains a buffer overflow vulnerability. The issue occurs when a non-contiguous buffer is passed to APIs that accept Python buffers (e.g., Hash.update()). The flaw is fixed in version 46.0.7.
- CVE-2026-69248Medium
The cryptography package for Python in versions 45.0.0 through 48.0.0 has a vulnerability in certificate chain verification. If an intermediate constrained CA permits the DNS name foo.example.com, and the leaf certificate has a wildcard *.example.com, the verifier accepts the chain, allowing escape outside permitted names. Fixed in version 49.0.0.
- CVE-2026-69247High
cryptography, a cryptographic library for Python, versions 44.0.0 through 50.0.0, is vulnerable to a Bleichenbacher-style attack. Functions pkcs7_decrypt_der, pkcs7_decrypt_pem, and pkcs7_decrypt_smime reveal differences in decrypting encryptedKey, which can be exploited to decrypt the content-encryption key. Exploitation requires a service auto-decrypting untrusted EnvelopedData, e.g., S/MIME gateways. Fixed in version 50.0.0.
- CVE-2026-26007Medium
The cryptography library for Python before version 46.0.5 does not verify that a public key point belongs to the expected prime-order subgroup. This missing validation allows an attacker to provide a point from a small-order subgroup, leading to private key leakage in ECDH and signature forgery in ECDSA. Only SECT curves are affected.
Original NVD description (English source)
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.