A Bleichenbacher type side-channel based padding oracle attack was found in the way nettle handles endian conversion of RSA decrypted PKCS#1 v1.5 data. An attacker who is able to run a process on the same physical core as the victim process, could use this flaw extract plaintext or in some cases downgrade any TLS connections to a vulnerable server.
Severity
CVSS 3.1
5.7 medium
CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:C/C:H/I:L/A:N
EPSS
1.5% chance of exploitation in the next 30 days; higher than 74% of CVEs (scores of 2026-10-31)