CVE-2026-48859

Name	CVE-2026-48859
Description	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.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
erlang (PTS)	bullseye	1:23.2.6+dfsg-1+deb11u1	fixed
	bullseye (security)	1:23.2.6+dfsg-1+deb11u4	fixed
	bookworm	1:25.2.3+dfsg-1+deb12u4	fixed
	bookworm (security)	1:25.2.3+dfsg-1+deb12u1	fixed
	trixie	1:27.3.4.1+dfsg-1+deb13u2	fixed
	forky, sid	1:29.0.2+dfsg-1	fixed

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
erlang	source	(unstable)	(not affected)

Notes

- erlang <not-affected> (Vulnerable code not present)
https://cna.erlef.org/cves/CVE-2026-48859.html
https://osv.dev/vulnerability/EEF-CVE-2026-48859
Introduced with: https://github.com/erlang/otp/commit/032d1bc9491a3975c68faf9bc7776115d6ae3005 (OTP-29.0-rc2)
Fixed by: https://github.com/erlang/otp/commit/c342092ef4b369bb409d5b71ac8fd83bab74aedf (OTP-29.0.2)