Medium (5.9). EPSS 1.3% chance of exploitation in the next 30 days.
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.
Severity
CVSS 3.1
5.9 medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
EPSS
1.3% chance of exploitation in the next 30 days; higher than 70% of CVEs (scores of 2026-10-31)