In Eclipse Milo versions 0.6.0 through 1.1.4, username-token processing returns distinguishable errors for invalid RSA PKCS#1 v1.5 padding and other authentication failures, allowing an on-path attacker who captures a victim's `Basic128Rsa15`-encrypted username token to use repeated unauthenticated `ActivateSession` requests as a padding oracle, recover the victim's password, and authenticate with the recovered credentials.
https://gitlab.eclipse.org/security/vulnerability-reports/-/work_items/598
https://gitlab.eclipse.org/security/cve-assignment/-/work_items/183
https://github.com/eclipse-milo/milo/commit/db59fae993a3a1bc66fffc8a2796d444b40285fb
Published: 2026-08-04
Updated: 2026-08-05
Base Score: 7.1
Vector: CVSS2#AV:N/AC:H/Au:N/C:C/I:C/A:N
Severity: High
Base Score: 7.4
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Severity: High
Base Score: 9.1
Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
Severity: Critical
EPSS: 0.00454