CVE-2026-48859

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.

CVSS 4.0

6.3CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

CVSS 3.1

5.3CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

EPSS

0.4% chance of exploitation in the next 30 days; higher than 28% of CVEs (scores of 2026-10-25)

CWE

CWE-208

Published

2026-06-10

Modified

2026-10-26

Record from

the NVD, synced 2026-10-26

Affected

• erlang:erlang\/otp
• erlang:erlang\/ssh

References

• https://cna.erlef.org/cves/CVE-2026-48859.html
• https://github.com/erlang/otp/commit/c342092ef4b369bb409d5b71ac8fd83bab74aedf
• https://github.com/erlang/otp/security/advisories/GHSA-3w6p-vwhf-wvp4
• https://osv.dev/vulnerability/EEF-CVE-2026-48859
• https://www.erlang.org/doc/system/versions.html#order-of-versions

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