CVE-2023-1732: Improper random reading in CIRCL

Vulnerability summary

CVE-2023-1732 is a high (CVSS 8.2) Improper Input Validation vulnerability in cloudflare circl. EPSS estimates a 0.39% chance of exploitation in the next 30 days, higher than 32.7% of scored vulnerabilities.

Timeline

1. 10-05-2023
   PublishedVulnerability first disclosed.
2. 27-01-2025
   Last modifiedVulnerability information updated.

Description

When sampling randomness for a shared secret, the implementation of Kyber and FrodoKEM, did not check whether crypto/rand.Read() returns an error. In rare deployment cases (error thrown by the Read() function), this could lead to a predictable shared secret. The tkn20 and blindrsa components did not check whether enough randomness was returned from the user provided randomness source. Typically the user provides crypto/rand.Reader, which in the vast majority of cases will always return the right number random bytes. In the cases where it does not, or the user provides a source that does not, the blinding for blindrsa is weak and integrity of the plaintext is not ensured in tkn20.

• CWE-20Improper Input ValidationThe product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
• CWE-755Improper Handling of Exceptional ConditionsThe product does not handle or incorrectly handles an exceptional condition.