An issue was discovered in compare_digest in Lib/hmac.py in Python through 3.9.1. Constant-time-defeating optimisations were possible in the accumulator variable in hmac.compare_digest.
{
"cpes": [
"cpe:2.3:a:python:python:*:*:*:*:*:*:*:*"
],
"severity": "Medium"
}