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High

PyCA Cryptography symmetrically encrypting large values can lead to integer overflow

  • Disclosed: 07.02.2021
  • Updated: 11.10.2026 12:19

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.

Affected software

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PlatformPackageVulnerable versionsFixed in
Python (PyPI) cryptography >= 3.1, < 3.3.2 3.3.2

References

CVSS score 9.1/10
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
Weakness (CWE)
CWE-190, CWE-787
Platform
Python (PyPI)
Package
cryptography
Disclosed
07.02.2021
Updated
11.10.2026 12:19

Sources and licenses

OSV / GitHub Advisory Database - PYSEC-2021-63 - PyPA Advisory Database; CC BY 4.0

OSV / GitHub Advisory Database - GHSA-rhm9-p9w5-fwm7 - CC BY 4.0

Vulnerability history: cryptography

All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.

All (24) in the archive
Total entries
24
First → latest
03.2017 08.2026
Without a fix
0
Exploited in attacks
0

Severity breakdown

  • High 12
  • Medium 7
  • Low 5

Disclosures per year

Severity:
  1. python-cryptography: Duplicate self-signed intermediates can cause exponential path-building
    High CVE-2026-69249 >= 42.0.0, < 49.0.0 49.0.0
  2. cryptography: PKCS#7 EnvelopedData decryption exposes a Bleichenbacher oracle through distinguishable errors and timing
    High CVE-2026-69247 >= 44.0.0, < 50.0.0 50.0.0
  3. Vulnerable OpenSSL included in cryptography wheels
    High · 7.5 ghsa-537c-gmf6-5ccf >= 0.5.0, < 48.0.1 48.0.1
  4. cryptography Vulnerable to a Subgroup Attack Due to Missing Subgroup Validation for SECT Curves
    High CVE-2026-26007 < 46.0.5 46.0.5
  5. cryptography NULL pointer dereference with pkcs12.serialize_key_and_certificates when called with a non-matching certificate and private key and an hmac_hash override
    High · 7.5 CVE-2024-26130 >= 38.0.0, < 42.0.4 42.0.4
  6. Python Cryptography package vulnerable to Bleichenbacher timing oracle attack
    High · 7.5 CVE-2023-50782 < 42.0.0 42.0.0
  7. cryptography mishandles SSH certificates
    High · 7.5 CVE-2023-38325 >= 40.0.0, < 41.0.2 41.0.2
  8. Vulnerable OpenSSL included in cryptography wheels
    High · 7.4 CVE-2023-0286 >= 0.8.1, < 39.0.1 39.0.1
  9. PyCA Cryptography symmetrically encrypting large values can lead to integer overflow this entry
    High · 9.1 CVE-2020-36242 >= 3.1, < 3.3.2 3.3.2
  10. RSA decryption vulnerable to Bleichenbacher timing vulnerability
    High · 5.9 CVE-2020-25659 < 3.2 3.2
  11. PyCA Cryptography vulnerable to GCM tag forgery
    High · 7.5 CVE-2018-10903 >= 1.9.0, < 2.3 2.3
  12. Improper input validation in cryptography
    High · 7.5 CVE-2016-9243 < 1.5.3 1.5.3

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