CVE-2020-36242: cryptography.io cryptography Integer Overflow or Wraparound

Vulnerability summary

CVE-2020-36242 is a critical (CVSS 9.1) Integer Overflow or Wraparound vulnerability in cryptography.io cryptography. EPSS estimates a 6.80% chance of exploitation in the next 30 days, higher than 94% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 07-02-2021
   PublishedVulnerability first disclosed.
2. 04-08-2024
   Last modifiedVulnerability information updated.

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.

• CWE-190Integer Overflow or WraparoundThe product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.
• CWE-787Out-of-bounds WriteThe product writes data past the end, or before the beginning, of the intended buffer.