CVE-2026-48859: Observable Timing Discrepancy vulnerability in Erlang/OTP ssh (ssh_auth, ssh_options modules) allows unauthenticated remote username enumeration via timing…

PriorityP335medium5.3CVSS 3.1

AVNACLPRNUINSUCLINAN

EPSS

0.35%

27.3th percentile

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 29.0.2 corresponding to ssh from 6.0 before 6.0.1.

Affected

5 ranges

Vendor	Product	Version range	Fixed in
erlang	erlang_otp	>= 29.0 < 29.0.2	29.0.2
erlang	erlang_ssh	>= 6.0 < 6.0.1	6.0.1
erlang	otp	>= 032d1bc9491a3975c68faf9bc7776115d6ae3005 < c342092ef4b369bb409d5b71ac8fd83bab74aedf	c342092ef4b369bb409d5b71ac8fd83bab74aedf
erlang	otp	>= 29.0 < 29.0.2	29.0.2
erlang	otp	>= 6.0 < 6.0.1	6.0.1

CVSS provenance

nvdv3.15.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

nvdv4.06.3MEDIUMCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Stop checking back — get the weekly exploitation signal.

Every Monday: what got weaponized or added to CISA KEV in the last seven days — each CVE cross-linked to its PoC, Nuclei template, and detection rule. Free, one email a week, unsubscribe in one click.