CVE-2026-48859: Erlang Erlang/otp

Medium severity, CVSS 5.3. EPSS: 0.6% chance of exploitation in the next 30 days.

Observable Timing Discrepancy vulnerability in Erlang/OTP ssh (ssh_auth, ssh_options modules) allows unauthenticated remote username enumeration via timing side-channel in password authentication. When the SSH daemon is configured with the user_passwords or password option, ssh_auth:check_password/3 performs a PBKDF2-SHA256 computation with 600,000 iterations (~300ms) for valid usernames, but returns immediately (~0ms) for invalid usernames via the ssh_options:get_password_option/2 path. This timing difference is detectable in a single authentication attempt and allows an unauthenticated attacker to distinguish valid from invalid usernames. The user_passwords and password options are documented as intended for test purposes; the recommended alternative is pwdfun, which is not affected by this vulnerability. This vulnerability is associated with program files lib/ssh/src/ssh_auth.erl and lib/ssh/src/ssh_options.erl. This issue affects OTP from OTP 29.0 before OTP 29.0.2, corresponding to ssh from 6.0 before 6.0.1.

Affected products

• Erlang Erlang/otp: from 29.0, before 29.0.2 (fixed in 29.0.2)
• Erlang Erlang/ssh: from 6.0, before 6.0.1 (fixed in 6.0.1)

Published 2026-06-10. Last modified 2026-09-08.