Observable Timing Discrepancy vulnerability in Erlang/OTP ssh (sshauth, sshoptions modules) allows unauthenticated remote username enumeration via timing side-channel in password authentication.
When the SSH daemon is configured with the userpasswords or password option, sshauth:checkpassword/3 performs a PBKDF2-SHA256 computation with 600,000 iterations (~300ms) for valid usernames, but returns immediately (~0ms) for invalid usernames via the sshoptions:getpasswordoption/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/sshauth.erl and lib/ssh/src/sshoptions.erl.
This issue affects OTP from OTP 29.0 before 29.0.2 corresponding to ssh from 6.0 before 6.0.1.
{
"unresolved_ranges": [
{
"source": "AFFECTED_FIELD",
"extracted_events": [
{
"introduced": "6.0"
},
{
"fixed": "6.0.1"
},
{
"introduced": "032d1bc9491a3975c68faf9bc7776115d6ae3005"
},
{
"fixed": "c342092ef4b369bb409d5b71ac8fd83bab74aedf"
}
]
}
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/48xxx/CVE-2026-48859.json",
"cna_assigner": "EEF",
"cwe_ids": [
"CWE-208"
]
}