CVE-2026-48859
SSH server timing side-channel in ssh_auth:check_password/3 allows unauthenticated username enumeration
At a glance
- Source
- NVD
- EPSS
- EPSS 0.35 % · percentile 29 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- EEF
- NVD status
- Modified
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 OTP 29.0.2, corresponding to ssh from 6.0 before 6.0.1.
Weaknesses (CWE)
- CWE-208 — Observable Timing Discrepancy
References
- https://github.com/erlang/otp/security/advisories/GHSA-3w6p-vwhf-wvp4
- https://cna.erlef.org/cves/CVE-2026-48859.html
- https://osv.dev/vulnerability/EEF-CVE-2026-48859
- https://www.erlang.org/doc/system/versions.html#order-of-versions
- https://github.com/erlang/otp/commit/c342092ef4b369bb409d5b71ac8fd83bab74aedf
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 4.0 | MEDIUM 6.3 | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N | EEF |
| CVSS 4.0 | MEDIUM 6.3 | CVSS: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 | NVD · 6b3ad84c-e1a6-4bf7-a703-f496b71e49db (Secondary) |
| CVSS 3.1 | MEDIUM 5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N | NVD · nvd@nist.gov (Primary) |
European references
- ENISA EUVD · EUVD-2026-36054
- GCVE · GCVE-0-2026-48859
Affected configurations (NVD CPE)
cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:*≥ 29.0 < 29.0.2cpe:2.3:a:erlang:erlang\/ssh:*:*:*:*:*:*:*:*≥ 6.0 < 6.0.1
Affected products
| Product | Versions |
|---|---|
| Erlang · OTP | affected 29.0 < 29.0.2 |
| Erlang · OTP | affected 6.0 < 6.0.1 |
| Erlang · OTP | affected 032d1bc9491a3975c68faf9bc7776115d6ae3005 < c342092ef4b369bb409d5b71ac8fd83bab74aedf |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |