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 v3 5.3 MEDIUM

5.3^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 3.9 / Impact : 1.4

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact LOW

Integrity Impact NONE

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://cna.erlef.org/cves/CVE-2026-48859.html	Mitigation Third Party Advisory
https://github.com/erlang/otp/commit/c342092ef4b369bb409d5b71ac8fd83bab74aedf	Patch
https://github.com/erlang/otp/security/advisories/GHSA-3w6p-vwhf-wvp4	Mitigation Vendor Advisory
https://osv.dev/vulnerability/EEF-CVE-2026-48859	Mitigation Third Party Advisory
https://www.erlang.org/doc/system/versions.html#order-of-versions	Product

Configurations

Configuration 1 (hide)

OR	cpe:2.3:a:erlang:erlang\/otp::::::::
	cpe:2.3:a:erlang:erlang\/ssh::::::::

History

No history.

Information

Published : 2026-06-10 16:17

Updated : 2026-09-08 01:17

NVD link : CVE-2026-48859

Mitre link : CVE-2026-48859

CVE.ORG link : CVE-2026-48859

JSON object : View

Products Affected

erlang

erlang\/ssh
erlang\/otp

CWE

CWE-208

Observable Timing Discrepancy

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"tags": ["Mitigation", "Third Party Advisory"], "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"}, {"url": "https://www.erlang.org/doc/system/versions.html#order-of-versions", "tags": ["Product"], "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"}], "vulnStatus": "Modified", "weaknesses": [{"type": "Secondary", "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "description": [{"lang": "en", "value": "CWE-208"}]}], "descriptions": [{"lang": "en", "value": "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.\n\nWhen 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.\n\nThe user_passwords and password options are documented as intended for test purposes; the recommended alternative is pwdfun, which is not affected by this vulnerability.\n\nThis vulnerability is associated with program files lib/ssh/src/ssh_auth.erl and lib/ssh/src/ssh_options.erl.\n\nThis issue affects OTP from OTP\u00a029.0 before OTP\u00a029.0.2, corresponding to ssh from 6.0 before 6.0.1."}], "lastModified": "2026-09-08T01:17:31.137", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "F4AB1573-4E81-4338-B65A-B3C94C7249FA", "versionEndExcluding": "29.0.2", "versionStartIncluding": "29.0"}, {"criteria": "cpe:2.3:a:erlang:erlang\\/ssh:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "0BF9A1F8-83F5-4BEB-A972-3AF5B15947EF", "versionEndExcluding": "6.0.1", "versionStartIncluding": "6.0"}], "operator": "OR"}]}], "sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"}