Critical (9.8). EPSS 0.8% chance of exploitation in the next 30 days.
In Rhonabwy through 1.1.13, HMAC signature verification uses a strcmp function that is vulnerable to side-channel attacks, because it stops the comparison when the first difference is spotted in the two signatures. (The fix uses gnutls_memcmp, which has constant-time execution.)
Severity
CVSS 3.1
9.8 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS
0.8% chance of exploitation in the next 30 days; higher than 57% of CVEs (scores of 2026-10-31)